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  • Plan Operator Tuesday round-up

    - by Rob Farley
    Eighteen posts for T-SQL Tuesday #43 this month, discussing Plan Operators. I put them together and made the following clickable plan. It’s 1000px wide, so I hope you have a monitor wide enough. Let me explain this plan for you (people’s names are the links to the articles on their blogs – the same links as in the plan above). It was clearly a SELECT statement. Wayne Sheffield (@dbawayne) wrote about that, so we start with a SELECT physical operator, leveraging the logical operator Wayne Sheffield. The SELECT operator calls the Paul White operator, discussed by Jason Brimhall (@sqlrnnr) in his post. The Paul White operator is quite remarkable, and can consume three streams of data. Let’s look at those streams. The first pulls data from a Table Scan – Boris Hristov (@borishristov)’s post – using parallel threads (Bradley Ball – @sqlballs) that pull the data eagerly through a Table Spool (Oliver Asmus – @oliverasmus). A scalar operation is also performed on it, thanks to Jeffrey Verheul (@devjef)’s Compute Scalar operator. The second stream of data applies Evil (I figured that must mean a procedural TVF, but could’ve been anything), courtesy of Jason Strate (@stratesql). It performs this Evil on the merging of parallel streams (Steve Jones – @way0utwest), which suck data out of a Switch (Paul White – @sql_kiwi). This Switch operator is consuming data from up to four lookups, thanks to Kalen Delaney (@sqlqueen), Rick Krueger (@dataogre), Mickey Stuewe (@sqlmickey) and Kathi Kellenberger (@auntkathi). Unfortunately Kathi’s name is a bit long and has been truncated, just like in real plans. The last stream performs a join of two others via a Nested Loop (Matan Yungman – @matanyungman). One pulls data from a Spool (my post – @rob_farley) populated from a Table Scan (Jon Morisi). The other applies a catchall operator (the catchall is because Tamera Clark (@tameraclark) didn’t specify any particular operator, and a catchall is what gets shown when SSMS doesn’t know what to show. Surprisingly, it’s showing the yellow one, which is about cursors. Hopefully that’s not what Tamera planned, but anyway...) to the output from an Index Seek operator (Sebastian Meine – @sqlity). Lastly, I think everyone put in 110% effort, so that’s what all the operators cost. That didn’t leave anything for me, unfortunately, but that’s okay. Also, because he decided to use the Paul White operator, Jason Brimhall gets 0%, and his 110% was given to Paul’s Switch operator post. I hope you’ve enjoyed this T-SQL Tuesday, and have learned something extra about Plan Operators. Keep your eye out for next month’s one by watching the Twitter Hashtag #tsql2sday, and why not contribute a post to the party? Big thanks to Adam Machanic as usual for starting all this. @rob_farley

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  • Security Issues with Single Page Apps

    - by Stephen.Walther
    Last week, I was asked to do a code review of a Single Page App built using the ASP.NET Web API, Durandal, and Knockout (good stuff!). In particular, I was asked to investigate whether there any special security issues associated with building a Single Page App which are not present in the case of a traditional server-side ASP.NET application. In this blog entry, I discuss two areas in which you need to exercise extra caution when building a Single Page App. I discuss how Single Page Apps are extra vulnerable to both Cross-Site Scripting (XSS) attacks and Cross-Site Request Forgery (CSRF) attacks. This goal of this blog post is NOT to persuade you to avoid writing Single Page Apps. I’m a big fan of Single Page Apps. Instead, the goal is to ensure that you are fully aware of some of the security issues related to Single Page Apps and ensure that you know how to guard against them. Cross-Site Scripting (XSS) Attacks According to WhiteHat Security, over 65% of public websites are open to XSS attacks. That’s bad. By taking advantage of XSS holes in a website, a hacker can steal your credit cards, passwords, or bank account information. Any website that redisplays untrusted information is open to XSS attacks. Let me give you a simple example. Imagine that you want to display the name of the current user on a page. To do this, you create the following server-side ASP.NET page located at http://MajorBank.com/SomePage.aspx: <%@Page Language="C#" %> <html> <head> <title>Some Page</title> </head> <body> Welcome <%= Request["username"] %> </body> </html> Nothing fancy here. Notice that the page displays the current username by using Request[“username”]. Using Request[“username”] displays the username regardless of whether the username is present in a cookie, a form field, or a query string variable. Unfortunately, by using Request[“username”] to redisplay untrusted information, you have now opened your website to XSS attacks. Here’s how. Imagine that an evil hacker creates the following link on another website (hackers.com): <a href="/SomePage.aspx?username=<script src=Evil.js></script>">Visit MajorBank</a> Notice that the link includes a query string variable named username and the value of the username variable is an HTML <SCRIPT> tag which points to a JavaScript file named Evil.js. When anyone clicks on the link, the <SCRIPT> tag will be injected into SomePage.aspx and the Evil.js script will be loaded and executed. What can a hacker do in the Evil.js script? Anything the hacker wants. For example, the hacker could display a popup dialog on the MajorBank.com site which asks the user to enter their password. The script could then post the password back to hackers.com and now the evil hacker has your secret password. ASP.NET Web Forms and ASP.NET MVC have two automatic safeguards against this type of attack: Request Validation and Automatic HTML Encoding. Protecting Coming In (Request Validation) In a server-side ASP.NET app, you are protected against the XSS attack described above by a feature named Request Validation. If you attempt to submit “potentially dangerous” content — such as a JavaScript <SCRIPT> tag — in a form field or query string variable then you get an exception. Unfortunately, Request Validation only applies to server-side apps. Request Validation does not help in the case of a Single Page App. In particular, the ASP.NET Web API does not pay attention to Request Validation. You can post any content you want – including <SCRIPT> tags – to an ASP.NET Web API action. For example, the following HTML page contains a form. When you submit the form, the form data is submitted to an ASP.NET Web API controller on the server using an Ajax request: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title></title> </head> <body> <form data-bind="submit:submit"> <div> <label> User Name: <input data-bind="value:user.userName" /> </label> </div> <div> <label> Email: <input data-bind="value:user.email" /> </label> </div> <div> <input type="submit" value="Submit" /> </div> </form> <script src="Scripts/jquery-1.7.1.js"></script> <script src="Scripts/knockout-2.1.0.js"></script> <script> var viewModel = { user: { userName: ko.observable(), email: ko.observable() }, submit: function () { $.post("/api/users", ko.toJS(this.user)); } }; ko.applyBindings(viewModel); </script> </body> </html> The form above is using Knockout to bind the form fields to a view model. When you submit the form, the view model is submitted to an ASP.NET Web API action on the server. Here’s the server-side ASP.NET Web API controller and model class: public class UsersController : ApiController { public HttpResponseMessage Post(UserViewModel user) { var userName = user.UserName; return Request.CreateResponse(HttpStatusCode.OK); } } public class UserViewModel { public string UserName { get; set; } public string Email { get; set; } } If you submit the HTML form, you don’t get an error. The “potentially dangerous” content is passed to the server without any exception being thrown. In the screenshot below, you can see that I was able to post a username form field with the value “<script>alert(‘boo’)</script”. So what this means is that you do not get automatic Request Validation in the case of a Single Page App. You need to be extra careful in a Single Page App about ensuring that you do not display untrusted content because you don’t have the Request Validation safety net which you have in a traditional server-side ASP.NET app. Protecting Going Out (Automatic HTML Encoding) Server-side ASP.NET also protects you from XSS attacks when you render content. By default, all content rendered by the razor view engine is HTML encoded. For example, the following razor view displays the text “<b>Hello!</b>” instead of the text “Hello!” in bold: @{ var message = "<b>Hello!</b>"; } @message   If you don’t want to render content as HTML encoded in razor then you need to take the extra step of using the @Html.Raw() helper. In a Web Form page, if you use <%: %> instead of <%= %> then you get automatic HTML Encoding: <%@ Page Language="C#" %> <% var message = "<b>Hello!</b>"; %> <%: message %> This automatic HTML Encoding will prevent many types of XSS attacks. It prevents <script> tags from being rendered and only allows &lt;script&gt; tags to be rendered which are useless for executing JavaScript. (This automatic HTML encoding does not protect you from all forms of XSS attacks. For example, you can assign the value “javascript:alert(‘evil’)” to the Hyperlink control’s NavigateUrl property and execute the JavaScript). The situation with Knockout is more complicated. If you use the Knockout TEXT binding then you get HTML encoded content. On the other hand, if you use the HTML binding then you do not: <!-- This JavaScript DOES NOT execute --> <div data-bind="text:someProp"></div> <!-- This Javacript DOES execute --> <div data-bind="html:someProp"></div> <script src="Scripts/jquery-1.7.1.js"></script> <script src="Scripts/knockout-2.1.0.js"></script> <script> var viewModel = { someProp : "<script>alert('Evil!')<" + "/script>" }; ko.applyBindings(viewModel); </script>   So, in the page above, the DIV element which uses the TEXT binding is safe from XSS attacks. According to the Knockout documentation: “Since this binding sets your text value using a text node, it’s safe to set any string value without risking HTML or script injection.” Just like server-side HTML encoding, Knockout does not protect you from all types of XSS attacks. For example, there is nothing in Knockout which prevents you from binding JavaScript to a hyperlink like this: <a data-bind="attr:{href:homePageUrl}">Go</a> <script src="Scripts/jquery-1.7.1.min.js"></script> <script src="Scripts/knockout-2.1.0.js"></script> <script> var viewModel = { homePageUrl: "javascript:alert('evil!')" }; ko.applyBindings(viewModel); </script> In the page above, the value “javascript:alert(‘evil’)” is bound to the HREF attribute using Knockout. When you click the link, the JavaScript executes. Cross-Site Request Forgery (CSRF) Attacks Cross-Site Request Forgery (CSRF) attacks rely on the fact that a session cookie does not expire until you close your browser. In particular, if you visit and login to MajorBank.com and then you navigate to Hackers.com then you will still be authenticated against MajorBank.com even after you navigate to Hackers.com. Because MajorBank.com cannot tell whether a request is coming from MajorBank.com or Hackers.com, Hackers.com can submit requests to MajorBank.com pretending to be you. For example, Hackers.com can post an HTML form from Hackers.com to MajorBank.com and change your email address at MajorBank.com. Hackers.com can post a form to MajorBank.com using your authentication cookie. After your email address has been changed, by using a password reset page at MajorBank.com, a hacker can access your bank account. To prevent CSRF attacks, you need some mechanism for detecting whether a request is coming from a page loaded from your website or whether the request is coming from some other website. The recommended way of preventing Cross-Site Request Forgery attacks is to use the “Synchronizer Token Pattern” as described here: https://www.owasp.org/index.php/Cross-Site_Request_Forgery_%28CSRF%29_Prevention_Cheat_Sheet When using the Synchronizer Token Pattern, you include a hidden input field which contains a random token whenever you display an HTML form. When the user opens the form, you add a cookie to the user’s browser with the same random token. When the user posts the form, you verify that the hidden form token and the cookie token match. Preventing Cross-Site Request Forgery Attacks with ASP.NET MVC ASP.NET gives you a helper and an action filter which you can use to thwart Cross-Site Request Forgery attacks. For example, the following razor form for creating a product shows how you use the @Html.AntiForgeryToken() helper: @model MvcApplication2.Models.Product <h2>Create Product</h2> @using (Html.BeginForm()) { @Html.AntiForgeryToken(); <div> @Html.LabelFor( p => p.Name, "Product Name:") @Html.TextBoxFor( p => p.Name) </div> <div> @Html.LabelFor( p => p.Price, "Product Price:") @Html.TextBoxFor( p => p.Price) </div> <input type="submit" /> } The @Html.AntiForgeryToken() helper generates a random token and assigns a serialized version of the same random token to both a cookie and a hidden form field. (Actually, if you dive into the source code, the AntiForgeryToken() does something a little more complex because it takes advantage of a user’s identity when generating the token). Here’s what the hidden form field looks like: <input name=”__RequestVerificationToken” type=”hidden” value=”NqqZGAmlDHh6fPTNR_mti3nYGUDgpIkCiJHnEEL59S7FNToyyeSo7v4AfzF2i67Cv0qTB1TgmZcqiVtgdkW2NnXgEcBc-iBts0x6WAIShtM1″ /> And here’s what the cookie looks like using the Google Chrome developer toolbar: You use the [ValidateAntiForgeryToken] action filter on the controller action which is the recipient of the form post to validate that the token in the hidden form field matches the token in the cookie. If the tokens don’t match then validation fails and you can’t post the form: public ActionResult Create() { return View(); } [ValidateAntiForgeryToken] [HttpPost] public ActionResult Create(Product productToCreate) { if (ModelState.IsValid) { // save product to db return RedirectToAction("Index"); } return View(); } How does this all work? Let’s imagine that a hacker has copied the Create Product page from MajorBank.com to Hackers.com – the hacker grabs the HTML source and places it at Hackers.com. Now, imagine that the hacker trick you into submitting the Create Product form from Hackers.com to MajorBank.com. You’ll get the following exception: The Cross-Site Request Forgery attack is blocked because the anti-forgery token included in the Create Product form at Hackers.com won’t match the anti-forgery token stored in the cookie in your browser. The tokens were generated at different times for different users so the attack fails. Preventing Cross-Site Request Forgery Attacks with a Single Page App In a Single Page App, you can’t prevent Cross-Site Request Forgery attacks using the same method as a server-side ASP.NET MVC app. In a Single Page App, HTML forms are not generated on the server. Instead, in a Single Page App, forms are loaded dynamically in the browser. Phil Haack has a blog post on this topic where he discusses passing the anti-forgery token in an Ajax header instead of a hidden form field. He also describes how you can create a custom anti-forgery token attribute to compare the token in the Ajax header and the token in the cookie. See: http://haacked.com/archive/2011/10/10/preventing-csrf-with-ajax.aspx Also, take a look at Johan’s update to Phil Haack’s original post: http://johan.driessen.se/posts/Updated-Anti-XSRF-Validation-for-ASP.NET-MVC-4-RC (Other server frameworks such as Rails and Django do something similar. For example, Rails uses an X-CSRF-Token to prevent CSRF attacks which you generate on the server – see http://excid3.com/blog/rails-tip-2-include-csrf-token-with-every-ajax-request/#.UTFtgDDkvL8 ). For example, if you are creating a Durandal app, then you can use the following razor view for your one and only server-side page: @{ Layout = null; } <!DOCTYPE html> <html> <head> <title>Index</title> </head> <body> @Html.AntiForgeryToken() <div id="applicationHost"> Loading app.... </div> @Scripts.Render("~/scripts/vendor") <script type="text/javascript" src="~/App/durandal/amd/require.js" data-main="/App/main"></script> </body> </html> Notice that this page includes a call to @Html.AntiForgeryToken() to generate the anti-forgery token. Then, whenever you make an Ajax request in the Durandal app, you can retrieve the anti-forgery token from the razor view and pass the token as a header: var csrfToken = $("input[name='__RequestVerificationToken']").val(); $.ajax({ headers: { __RequestVerificationToken: csrfToken }, type: "POST", dataType: "json", contentType: 'application/json; charset=utf-8', url: "/api/products", data: JSON.stringify({ name: "Milk", price: 2.33 }), statusCode: { 200: function () { alert("Success!"); } } }); Use the following code to create an action filter which you can use to match the header and cookie tokens: using System.Linq; using System.Net.Http; using System.Web.Helpers; using System.Web.Http.Controllers; namespace MvcApplication2.Infrastructure { public class ValidateAjaxAntiForgeryToken : System.Web.Http.AuthorizeAttribute { protected override bool IsAuthorized(HttpActionContext actionContext) { var headerToken = actionContext .Request .Headers .GetValues("__RequestVerificationToken") .FirstOrDefault(); ; var cookieToken = actionContext .Request .Headers .GetCookies() .Select(c => c[AntiForgeryConfig.CookieName]) .FirstOrDefault(); // check for missing cookie or header if (cookieToken == null || headerToken == null) { return false; } // ensure that the cookie matches the header try { AntiForgery.Validate(cookieToken.Value, headerToken); } catch { return false; } return base.IsAuthorized(actionContext); } } } Notice that the action filter derives from the base AuthorizeAttribute. The ValidateAjaxAntiForgeryToken only works when the user is authenticated and it will not work for anonymous requests. Add the action filter to your ASP.NET Web API controller actions like this: [ValidateAjaxAntiForgeryToken] public HttpResponseMessage PostProduct(Product productToCreate) { // add product to db return Request.CreateResponse(HttpStatusCode.OK); } After you complete these steps, it won’t be possible for a hacker to pretend to be you at Hackers.com and submit a form to MajorBank.com. The header token used in the Ajax request won’t travel to Hackers.com. This approach works, but I am not entirely happy with it. The one thing that I don’t like about this approach is that it creates a hard dependency on using razor. Your single page in your Single Page App must be generated from a server-side razor view. A better solution would be to generate the anti-forgery token in JavaScript. Unfortunately, until all browsers support a way to generate cryptographically strong random numbers – for example, by supporting the window.crypto.getRandomValues() method — there is no good way to generate anti-forgery tokens in JavaScript. So, at least right now, the best solution for generating the tokens is the server-side solution with the (regrettable) dependency on razor. Conclusion The goal of this blog entry was to explore some ways in which you need to handle security differently in the case of a Single Page App than in the case of a traditional server app. In particular, I focused on how to prevent Cross-Site Scripting and Cross-Site Request Forgery attacks in the case of a Single Page App. I want to emphasize that I am not suggesting that Single Page Apps are inherently less secure than server-side apps. Whatever type of web application you build – regardless of whether it is a Single Page App, an ASP.NET MVC app, an ASP.NET Web Forms app, or a Rails app – you must constantly guard against security vulnerabilities.

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  • SQL SERVER – SQLServer Quiz 2011 – Do you know your execution plan – Two questions – One Answer

    - by pinaldave
    My friend Jacob Sebastian has SQL Server Quiz 2011 launched. This time when he asked me to come up with quiz question – I wanted to come up with something which is new and make participant to think about it. After carefully thinking I come with question which I really like to solve myself. Here is the details: 1) Using Single table only Once in Single SELECT statement generate execution plan which have JOIN operator. Explain the reason for the same. 2) Using Single table only Once in Single SELECT statement generate execution plan which have parallelism operator. Explain the reason for the same. Bonus: Create a single query which satisfy both of the above statement. To answer this question and win exciting gifts please visit the SQL Server Quiz website. Reference: Pinal Dave (http://blog.SQLAuthority.com)   Filed under: Pinal Dave, PostADay, Readers Contribution, Readers Question, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology

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  • How to Sync Any Folder With SkyDrive on Windows 8.1

    - by Chris Hoffman
    Before Windows 8.1, it was possible to sync any folder on your computer with SkyDrive using symbolic links. This method no longer works now that SkyDrive is baked into Windows 8.1, but there are other tricks you can use. Creating a symbolic link or directory junction inside your SkyDrive folder will give you an empty folder in your SkyDrive cloud storage. Confusingly, the files will appear inside the SkyDrive Modern app as if they were being synced, but they aren’t. The Solution With SkyDrive refusing to understand and accept symbolic links in its own folder, the best option is probably to use symbolic links anyway — but in reverse. For example, let’s say you have a program that automatically saves important data to a folder anywhere on your hard drive — whether it’s C:\Users\USER\Documents\, C:\Program\Data, or anywhere else. Rather than trying to trick SkyDrive into understanding a symbolic link, we could instead move the actual folder itself to SkyDrive and then use a symbolic link at the folder’s original location to trick the original program. This may not work for every single program out there. But it will likely work for most programs, which use standard Windows API calls to access folders and save files. We’re just flipping the old solution here — we can’t trick SkyDrive anymore, so let’s try to trick other programs instead. Moving a Folder and Creating a Symbolic Link First, ensure no program is using the external folder. For example, if it’s a program data or settings folder, close the program that’s using the folder. Next, simply move the folder to your SkyDrive folder. Right-click the external folder, select Cut, go to the SkyDrive folder, right-click and select Paste. The folder will now be located in the SkyDrive folder itself, so it will sync normally. Next, open a Command Prompt window as Administrator. Right-click the Start button on the taskbar or press Windows Key + X and select Command Prompt (Administrator) to open it. Run the following command to create a symbolic link at the original location of the folder: mklink /d “C:\Original\Folder\Location” “C:\Users\NAME\SkyDrive\FOLDERNAME\” Enter the correct paths for the exact location of the original folder and the current location of the folder in your SkyDrive. Windows will then create a symbolic link at the folder’s original location. Most programs should hopefully be tricked by this symbolic location, saving their files directly to SkyDrive. You can test this yourself. Put a file into the folder at its original location. It will be saved to SkyDrive and sync normally, appearing in your SkyDrive storage online. One downside here is that you won’t be able to save a file onto SkyDrive without it taking up space on the same hard drive SkyDrive is on. You won’t be able to scatter folders across multiple hard drives and sync them all. However, you could always change the location of the SkyDrive folder on Windows 8.1 and put it on a drive with a larger amount of free space. To do this, right-click the SkyDrive folder in File Explorer, select Properties, and use the options on the Location tab. You could even use Storage Spaces to combine the drives into one larger drive. Automatically Copy the Original Files to SkyDrive Another option would be to run a program that automatically copies files from another folder on your computer to your SkyDrive folder. For example, let’s say you want to sync copies of important log files that a program creates in a specific folder. You could use a program that allows you to schedule automatic folder-mirroring, configuring the program to regularly copy the contents of your log folder to your SkyDrive folder. This may be a useful alternative for some use cases, although it isn’t the same as standard syncing. You’ll end up with two copies of the files taking up space on your system, which won’t be ideal for large files. The files also won’t be instantly uploaded to your SkyDrive storage after they’re created, but only after the scheduled task runs. There are many options for this, including Microsoft’s own SyncToy, which continues to work on Windows 8. If you were using the symbolic link trick to automatically sync copies of PC game save files with SkyDrive, you could just install GameSave Manager. It can be configured to automatically create backup copies of your computer’s PC game save files on a schedule, saving them to SkyDrive where they’ll be synced and backed up online. SkyDrive support was completely rewritten for Windows 8.1, so it’s not surprising that this trick no longer works. The ability to use symbolic links in previous versions of SkyDrive was never officially supported, so it’s not surprising to see it break after a rewrite. None of the methods above are as convenient and quick as the old symbolic link method, but they’re the best we can do with the SkyDrive integration Microsoft has given us in Windows 8.1. It’s still possible to use symbolic links to easily sync other folders with competing cloud storage services like Dropbox and Google Drive, so you may want to consider switching away from SkyDrive if this feature is critical to you.     

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  • C#/.NET Little Wonders: Fun With Enum Methods

    - by James Michael Hare
    Once again lets dive into the Little Wonders of .NET, those small things in the .NET languages and BCL classes that make development easier by increasing readability, maintainability, and/or performance. So probably every one of us has used an enumerated type at one time or another in a C# program.  The enumerated types we create are a great way to represent that a value can be one of a set of discrete values (or a combination of those values in the case of bit flags). But the power of enum types go far beyond simple assignment and comparison, there are many methods in the Enum class (that all enum types “inherit” from) that can give you even more power when dealing with them. IsDefined() – check if a given value exists in the enum Are you reading a value for an enum from a data source, but are unsure if it is actually a valid value or not?  Casting won’t tell you this, and Parse() isn’t guaranteed to balk either if you give it an int or a combination of flags.  So what can we do? Let’s assume we have a small enum like this for result codes we want to return back from our business logic layer: 1: public enum ResultCode 2: { 3: Success, 4: Warning, 5: Error 6: } In this enum, Success will be zero (unless given another value explicitly), Warning will be one, and Error will be two. So what happens if we have code like this where perhaps we’re getting the result code from another data source (could be database, could be web service, etc)? 1: public ResultCode PerformAction() 2: { 3: // set up and call some method that returns an int. 4: int result = ResultCodeFromDataSource(); 5:  6: // this will suceed even if result is < 0 or > 2. 7: return (ResultCode) result; 8: } So what happens if result is –1 or 4?  Well, the cast does not fail, so what we end up with would be an instance of a ResultCode that would have a value that’s outside of the bounds of the enum constants we defined. This means if you had a block of code like: 1: switch (result) 2: { 3: case ResultType.Success: 4: // do success stuff 5: break; 6:  7: case ResultType.Warning: 8: // do warning stuff 9: break; 10:  11: case ResultType.Error: 12: // do error stuff 13: break; 14: } That you would hit none of these blocks (which is a good argument for always having a default in a switch by the way). So what can you do?  Well, there is a handy static method called IsDefined() on the Enum class which will tell you if an enum value is defined.  1: public ResultCode PerformAction() 2: { 3: int result = ResultCodeFromDataSource(); 4:  5: if (!Enum.IsDefined(typeof(ResultCode), result)) 6: { 7: throw new InvalidOperationException("Enum out of range."); 8: } 9:  10: return (ResultCode) result; 11: } In fact, this is often recommended after you Parse() or cast a value to an enum as there are ways for values to get past these methods that may not be defined. If you don’t like the syntax of passing in the type of the enum, you could clean it up a bit by creating an extension method instead that would allow you to call IsDefined() off any isntance of the enum: 1: public static class EnumExtensions 2: { 3: // helper method that tells you if an enum value is defined for it's enumeration 4: public static bool IsDefined(this Enum value) 5: { 6: return Enum.IsDefined(value.GetType(), value); 7: } 8: }   HasFlag() – an easier way to see if a bit (or bits) are set Most of us who came from the land of C programming have had to deal extensively with bit flags many times in our lives.  As such, using bit flags may be almost second nature (for a quick refresher on bit flags in enum types see one of my old posts here). However, in higher-level languages like C#, the need to manipulate individual bit flags is somewhat diminished, and the code to check for bit flag enum values may be obvious to an advanced developer but cryptic to a novice developer. For example, let’s say you have an enum for a messaging platform that contains bit flags: 1: // usually, we pluralize flags enum type names 2: [Flags] 3: public enum MessagingOptions 4: { 5: None = 0, 6: Buffered = 0x01, 7: Persistent = 0x02, 8: Durable = 0x04, 9: Broadcast = 0x08 10: } We can combine these bit flags using the bitwise OR operator (the ‘|’ pipe character): 1: // combine bit flags using 2: var myMessenger = new Messenger(MessagingOptions.Buffered | MessagingOptions.Broadcast); Now, if we wanted to check the flags, we’d have to test then using the bit-wise AND operator (the ‘&’ character): 1: if ((options & MessagingOptions.Buffered) == MessagingOptions.Buffered) 2: { 3: // do code to set up buffering... 4: // ... 5: } While the ‘|’ for combining flags is easy enough to read for advanced developers, the ‘&’ test tends to be easy for novice developers to get wrong.  First of all you have to AND the flag combination with the value, and then typically you should test against the flag combination itself (and not just for a non-zero)!  This is because the flag combination you are testing with may combine multiple bits, in which case if only one bit is set, the result will be non-zero but not necessarily all desired bits! Thanks goodness in .NET 4.0 they gave us the HasFlag() method.  This method can be called from an enum instance to test to see if a flag is set, and best of all you can avoid writing the bit wise logic yourself.  Not to mention it will be more readable to a novice developer as well: 1: if (options.HasFlag(MessagingOptions.Buffered)) 2: { 3: // do code to set up buffering... 4: // ... 5: } It is much more concise and unambiguous, thus increasing your maintainability and readability. It would be nice to have a corresponding SetFlag() method, but unfortunately generic types don’t allow you to specialize on Enum, which makes it a bit more difficult.  It can be done but you have to do some conversions to numeric and then back to the enum which makes it less of a payoff than having the HasFlag() method.  But if you want to create it for symmetry, it would look something like this: 1: public static T SetFlag<T>(this Enum value, T flags) 2: { 3: if (!value.GetType().IsEquivalentTo(typeof(T))) 4: { 5: throw new ArgumentException("Enum value and flags types don't match."); 6: } 7:  8: // yes this is ugly, but unfortunately we need to use an intermediate boxing cast 9: return (T)Enum.ToObject(typeof (T), Convert.ToUInt64(value) | Convert.ToUInt64(flags)); 10: } Note that since the enum types are value types, we need to assign the result to something (much like string.Trim()).  Also, you could chain several SetFlag() operations together or create one that takes a variable arg list if desired. Parse() and ToString() – transitioning from string to enum and back Sometimes, you may want to be able to parse an enum from a string or convert it to a string - Enum has methods built in to let you do this.  Now, many may already know this, but may not appreciate how much power are in these two methods. For example, if you want to parse a string as an enum, it’s easy and works just like you’d expect from the numeric types: 1: string optionsString = "Persistent"; 2:  3: // can use Enum.Parse, which throws if finds something it doesn't like... 4: var result = (MessagingOptions)Enum.Parse(typeof (MessagingOptions), optionsString); 5:  6: if (result == MessagingOptions.Persistent) 7: { 8: Console.WriteLine("It worked!"); 9: } Note that Enum.Parse() will throw if it finds a value it doesn’t like.  But the values it likes are fairly flexible!  You can pass in a single value, or a comma separated list of values for flags and it will parse them all and set all bits: 1: // for string values, can have one, or comma separated. 2: string optionsString = "Persistent, Buffered"; 3:  4: var result = (MessagingOptions)Enum.Parse(typeof (MessagingOptions), optionsString); 5:  6: if (result.HasFlag(MessagingOptions.Persistent) && result.HasFlag(MessagingOptions.Buffered)) 7: { 8: Console.WriteLine("It worked!"); 9: } Or you can parse in a string containing a number that represents a single value or combination of values to set: 1: // 3 is the combination of Buffered (0x01) and Persistent (0x02) 2: var optionsString = "3"; 3:  4: var result = (MessagingOptions) Enum.Parse(typeof (MessagingOptions), optionsString); 5:  6: if (result.HasFlag(MessagingOptions.Persistent) && result.HasFlag(MessagingOptions.Buffered)) 7: { 8: Console.WriteLine("It worked again!"); 9: } And, if you really aren’t sure if the parse will work, and don’t want to handle an exception, you can use TryParse() instead: 1: string optionsString = "Persistent, Buffered"; 2: MessagingOptions result; 3:  4: // try parse returns true if successful, and takes an out parm for the result 5: if (Enum.TryParse(optionsString, out result)) 6: { 7: if (result.HasFlag(MessagingOptions.Persistent) && result.HasFlag(MessagingOptions.Buffered)) 8: { 9: Console.WriteLine("It worked!"); 10: } 11: } So we covered parsing a string to an enum, what about reversing that and converting an enum to a string?  The ToString() method is the obvious and most basic choice for most of us, but did you know you can pass a format string for enum types that dictate how they are written as a string?: 1: MessagingOptions value = MessagingOptions.Buffered | MessagingOptions.Persistent; 2:  3: // general format, which is the default, 4: Console.WriteLine("Default : " + value); 5: Console.WriteLine("G (default): " + value.ToString("G")); 6:  7: // Flags format, even if type does not have Flags attribute. 8: Console.WriteLine("F (flags) : " + value.ToString("F")); 9:  10: // integer format, value as number. 11: Console.WriteLine("D (num) : " + value.ToString("D")); 12:  13: // hex format, value as hex 14: Console.WriteLine("X (hex) : " + value.ToString("X")); Which displays: 1: Default : Buffered, Persistent 2: G (default): Buffered, Persistent 3: F (flags) : Buffered, Persistent 4: D (num) : 3 5: X (hex) : 00000003 Now, you may not really see a difference here between G and F because I used a [Flags] enum, the difference is that the “F” option treats the enum as if it were flags even if the [Flags] attribute is not present.  Let’s take a non-flags enum like the ResultCode used earlier: 1: // yes, we can do this even if it is not [Flags] enum. 2: ResultCode value = ResultCode.Warning | ResultCode.Error; And if we run that through the same formats again we get: 1: Default : 3 2: G (default): 3 3: F (flags) : Warning, Error 4: D (num) : 3 5: X (hex) : 00000003 Notice that since we had multiple values combined, but it was not a [Flags] marked enum, the G and default format gave us a number instead of a value name.  This is because the value was not a valid single-value constant of the enum.  However, using the F flags format string, it broke out the value into its component flags even though it wasn’t marked [Flags]. So, if you want to get an enum to display appropriately for whether or not it has the [Flags] attribute, use G which is the default.  If you always want it to attempt to break down the flags, use F.  For numeric output, obviously D or  X are the best choice depending on whether you want decimal or hex. Summary Hopefully, you learned a couple of new tricks with using the Enum class today!  I’ll add more little wonders as I think of them and thanks for all the invaluable input!   Technorati Tags: C#,.NET,Little Wonders,Enum,BlackRabbitCoder

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  • Plan Caching and Query Memory Part I – When not to use stored procedure or other plan caching mechanisms like sp_executesql or prepared statement

    - by sqlworkshops
      The most common performance mistake SQL Server developers make: SQL Server estimates memory requirement for queries at compilation time. This mechanism is fine for dynamic queries that need memory, but not for queries that cache the plan. With dynamic queries the plan is not reused for different set of parameters values / predicates and hence different amount of memory can be estimated based on different set of parameter values / predicates. Common memory allocating queries are that perform Sort and do Hash Match operations like Hash Join or Hash Aggregation or Hash Union. This article covers Sort with examples. It is recommended to read Plan Caching and Query Memory Part II after this article which covers Hash Match operations.   When the plan is cached by using stored procedure or other plan caching mechanisms like sp_executesql or prepared statement, SQL Server estimates memory requirement based on first set of execution parameters. Later when the same stored procedure is called with different set of parameter values, the same amount of memory is used to execute the stored procedure. This might lead to underestimation / overestimation of memory on plan reuse, overestimation of memory might not be a noticeable issue for Sort operations, but underestimation of memory will lead to spill over tempdb resulting in poor performance.   This article covers underestimation / overestimation of memory for Sort. Plan Caching and Query Memory Part II covers underestimation / overestimation for Hash Match operation. It is important to note that underestimation of memory for Sort and Hash Match operations lead to spill over tempdb and hence negatively impact performance. Overestimation of memory affects the memory needs of other concurrently executing queries. In addition, it is important to note, with Hash Match operations, overestimation of memory can actually lead to poor performance.   To read additional articles I wrote click here.   In most cases it is cheaper to pay for the compilation cost of dynamic queries than huge cost for spill over tempdb, unless memory requirement for a stored procedure does not change significantly based on predicates.   The best way to learn is to practice. To create the below tables and reproduce the behavior, join the mailing list by using this link: www.sqlworkshops.com/ml and I will send you the table creation script. Most of these concepts are also covered in our webcasts: www.sqlworkshops.com/webcasts   Enough theory, let’s see an example where we sort initially 1 month of data and then use the stored procedure to sort 6 months of data.   Let’s create a stored procedure that sorts customers by name within certain date range.   --Example provided by www.sqlworkshops.com create proc CustomersByCreationDate @CreationDateFrom datetime, @CreationDateTo datetime as begin       declare @CustomerID int, @CustomerName varchar(48), @CreationDate datetime       select @CustomerName = c.CustomerName, @CreationDate = c.CreationDate from Customers c             where c.CreationDate between @CreationDateFrom and @CreationDateTo             order by c.CustomerName       option (maxdop 1)       end go Let’s execute the stored procedure initially with 1 month date range.   set statistics time on go --Example provided by www.sqlworkshops.com exec CustomersByCreationDate '2001-01-01', '2001-01-31' go The stored procedure took 48 ms to complete.     The stored procedure was granted 6656 KB based on 43199.9 rows being estimated.       The estimated number of rows, 43199.9 is similar to actual number of rows 43200 and hence the memory estimation should be ok.       There was no Sort Warnings in SQL Profiler.      Now let’s execute the stored procedure with 6 month date range. --Example provided by www.sqlworkshops.com exec CustomersByCreationDate '2001-01-01', '2001-06-30' go The stored procedure took 679 ms to complete.      The stored procedure was granted 6656 KB based on 43199.9 rows being estimated.      The estimated number of rows, 43199.9 is way different from the actual number of rows 259200 because the estimation is based on the first set of parameter value supplied to the stored procedure which is 1 month in our case. This underestimation will lead to sort spill over tempdb, resulting in poor performance.      There was Sort Warnings in SQL Profiler.    To monitor the amount of data written and read from tempdb, one can execute select num_of_bytes_written, num_of_bytes_read from sys.dm_io_virtual_file_stats(2, NULL) before and after the stored procedure execution, for additional information refer to the webcast: www.sqlworkshops.com/webcasts.     Let’s recompile the stored procedure and then let’s first execute the stored procedure with 6 month date range.  In a production instance it is not advisable to use sp_recompile instead one should use DBCC FREEPROCCACHE (plan_handle). This is due to locking issues involved with sp_recompile, refer to our webcasts for further details.   exec sp_recompile CustomersByCreationDate go --Example provided by www.sqlworkshops.com exec CustomersByCreationDate '2001-01-01', '2001-06-30' go Now the stored procedure took only 294 ms instead of 679 ms.    The stored procedure was granted 26832 KB of memory.      The estimated number of rows, 259200 is similar to actual number of rows of 259200. Better performance of this stored procedure is due to better estimation of memory and avoiding sort spill over tempdb.      There was no Sort Warnings in SQL Profiler.       Now let’s execute the stored procedure with 1 month date range.   --Example provided by www.sqlworkshops.com exec CustomersByCreationDate '2001-01-01', '2001-01-31' go The stored procedure took 49 ms to complete, similar to our very first stored procedure execution.     This stored procedure was granted more memory (26832 KB) than necessary memory (6656 KB) based on 6 months of data estimation (259200 rows) instead of 1 month of data estimation (43199.9 rows). This is because the estimation is based on the first set of parameter value supplied to the stored procedure which is 6 months in this case. This overestimation did not affect performance, but it might affect performance of other concurrent queries requiring memory and hence overestimation is not recommended. This overestimation might affect performance Hash Match operations, refer to article Plan Caching and Query Memory Part II for further details.    Let’s recompile the stored procedure and then let’s first execute the stored procedure with 2 day date range. exec sp_recompile CustomersByCreationDate go --Example provided by www.sqlworkshops.com exec CustomersByCreationDate '2001-01-01', '2001-01-02' go The stored procedure took 1 ms.      The stored procedure was granted 1024 KB based on 1440 rows being estimated.      There was no Sort Warnings in SQL Profiler.      Now let’s execute the stored procedure with 6 month date range. --Example provided by www.sqlworkshops.com exec CustomersByCreationDate '2001-01-01', '2001-06-30' go   The stored procedure took 955 ms to complete, way higher than 679 ms or 294ms we noticed before.      The stored procedure was granted 1024 KB based on 1440 rows being estimated. But we noticed in the past this stored procedure with 6 month date range needed 26832 KB of memory to execute optimally without spill over tempdb. This is clear underestimation of memory and the reason for the very poor performance.      There was Sort Warnings in SQL Profiler. Unlike before this was a Multiple pass sort instead of Single pass sort. This occurs when granted memory is too low.      Intermediate Summary: This issue can be avoided by not caching the plan for memory allocating queries. Other possibility is to use recompile hint or optimize for hint to allocate memory for predefined date range.   Let’s recreate the stored procedure with recompile hint. --Example provided by www.sqlworkshops.com drop proc CustomersByCreationDate go create proc CustomersByCreationDate @CreationDateFrom datetime, @CreationDateTo datetime as begin       declare @CustomerID int, @CustomerName varchar(48), @CreationDate datetime       select @CustomerName = c.CustomerName, @CreationDate = c.CreationDate from Customers c             where c.CreationDate between @CreationDateFrom and @CreationDateTo             order by c.CustomerName       option (maxdop 1, recompile)       end go Let’s execute the stored procedure initially with 1 month date range and then with 6 month date range. --Example provided by www.sqlworkshops.com exec CustomersByCreationDate '2001-01-01', '2001-01-30' exec CustomersByCreationDate '2001-01-01', '2001-06-30' go The stored procedure took 48ms and 291 ms in line with previous optimal execution times.      The stored procedure with 1 month date range has good estimation like before.      The stored procedure with 6 month date range also has good estimation and memory grant like before because the query was recompiled with current set of parameter values.      The compilation time and compilation CPU of 1 ms is not expensive in this case compared to the performance benefit.     Let’s recreate the stored procedure with optimize for hint of 6 month date range.   --Example provided by www.sqlworkshops.com drop proc CustomersByCreationDate go create proc CustomersByCreationDate @CreationDateFrom datetime, @CreationDateTo datetime as begin       declare @CustomerID int, @CustomerName varchar(48), @CreationDate datetime       select @CustomerName = c.CustomerName, @CreationDate = c.CreationDate from Customers c             where c.CreationDate between @CreationDateFrom and @CreationDateTo             order by c.CustomerName       option (maxdop 1, optimize for (@CreationDateFrom = '2001-01-01', @CreationDateTo ='2001-06-30'))       end go Let’s execute the stored procedure initially with 1 month date range and then with 6 month date range.   --Example provided by www.sqlworkshops.com exec CustomersByCreationDate '2001-01-01', '2001-01-30' exec CustomersByCreationDate '2001-01-01', '2001-06-30' go The stored procedure took 48ms and 291 ms in line with previous optimal execution times.    The stored procedure with 1 month date range has overestimation of rows and memory. This is because we provided hint to optimize for 6 months of data.      The stored procedure with 6 month date range has good estimation and memory grant because we provided hint to optimize for 6 months of data.       Let’s execute the stored procedure with 12 month date range using the currently cashed plan for 6 month date range. --Example provided by www.sqlworkshops.com exec CustomersByCreationDate '2001-01-01', '2001-12-31' go The stored procedure took 1138 ms to complete.      2592000 rows were estimated based on optimize for hint value for 6 month date range. Actual number of rows is 524160 due to 12 month date range.      The stored procedure was granted enough memory to sort 6 month date range and not 12 month date range, so there will be spill over tempdb.      There was Sort Warnings in SQL Profiler.      As we see above, optimize for hint cannot guarantee enough memory and optimal performance compared to recompile hint.   This article covers underestimation / overestimation of memory for Sort. Plan Caching and Query Memory Part II covers underestimation / overestimation for Hash Match operation. It is important to note that underestimation of memory for Sort and Hash Match operations lead to spill over tempdb and hence negatively impact performance. Overestimation of memory affects the memory needs of other concurrently executing queries. In addition, it is important to note, with Hash Match operations, overestimation of memory can actually lead to poor performance.   Summary: Cached plan might lead to underestimation or overestimation of memory because the memory is estimated based on first set of execution parameters. It is recommended not to cache the plan if the amount of memory required to execute the stored procedure has a wide range of possibilities. One can mitigate this by using recompile hint, but that will lead to compilation overhead. However, in most cases it might be ok to pay for compilation rather than spilling sort over tempdb which could be very expensive compared to compilation cost. The other possibility is to use optimize for hint, but in case one sorts more data than hinted by optimize for hint, this will still lead to spill. On the other side there is also the possibility of overestimation leading to unnecessary memory issues for other concurrently executing queries. In case of Hash Match operations, this overestimation of memory might lead to poor performance. When the values used in optimize for hint are archived from the database, the estimation will be wrong leading to worst performance, so one has to exercise caution before using optimize for hint, recompile hint is better in this case. I explain these concepts with detailed examples in my webcasts (www.sqlworkshops.com/webcasts), I recommend you to watch them. The best way to learn is to practice. To create the above tables and reproduce the behavior, join the mailing list at www.sqlworkshops.com/ml and I will send you the relevant SQL Scripts.     Register for the upcoming 3 Day Level 400 Microsoft SQL Server 2008 and SQL Server 2005 Performance Monitoring & Tuning Hands-on Workshop in London, United Kingdom during March 15-17, 2011, click here to register / Microsoft UK TechNet.These are hands-on workshops with a maximum of 12 participants and not lectures. For consulting engagements click here.     Disclaimer and copyright information:This article refers to organizations and products that may be the trademarks or registered trademarks of their various owners. Copyright of this article belongs to R Meyyappan / www.sqlworkshops.com. You may freely use the ideas and concepts discussed in this article with acknowledgement (www.sqlworkshops.com), but you may not claim any of it as your own work. This article is for informational purposes only; you use any of the suggestions given here entirely at your own risk.   R Meyyappan [email protected] LinkedIn: http://at.linkedin.com/in/rmeyyappan

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  • Find only physical network adapters with WMI Win32_NetworkAdapter class

    - by Mladen Prajdic
    WMI is Windows Management Instrumentation infrastructure for managing data and machines. We can access it by using WQL (WMI querying language or SQL for WMI). One thing to remember from the WQL link is that it doesn't support ORDER BY. This means that when you do SELECT * FROM wmiObject, the returned order of the objects is not guaranteed. It can return adapters in different order based on logged-in user, permissions of that user, etc… This is not documented anywhere that I've looked and is derived just from my observations. To get network adapters we have to query the Win32_NetworkAdapter class. This returns us all network adapters that windows detect, real and virtual ones, however it only supplies IPv4 data. I've tried various methods of combining properties that are common on all systems since Windows XP. The first thing to do to remove all virtual adapters (like tunneling, WAN miniports, etc…) created by Microsoft. We do this by adding WHERE Manufacturer!='Microsoft' to our WMI query. This greatly narrows the number of adapters we have to work with. Just on my machine it went from 20 adapters to 5. What was left were one real physical Realtek LAN adapter, 2 virtual adapters installed by VMware and 2 virtual adapters installed by VirtualBox. If you read the Win32_NetworkAdapter help page you'd notice that there's an AdapterType that enumerates various adapter types like LAN or Wireless and AdapterTypeID that gives you the same information as AdapterType only in integer form. The dirty little secret is that these 2 properties don't work. They are both hardcoded, AdapterTypeID to "0" and AdapterType to "Ethernet 802.3". The only exceptions I've seen so far are adapters that have no values at all for the two properties, "RAS Async Adapter" that has values of AdapterType = "Wide Area Network" and AdapterTypeID = "3" and various tunneling adapters that have values of AdapterType = "Tunnel" and AdapterTypeID = "15". In the help docs there isn't even a value for 15. So this property was of no help. Next property to give hope is NetConnectionId. This is the name of the network connection as it appears in the Control Panel -> Network Connections. Problem is this value is also localized into various languages and can have different names for different connection. So both of these properties don't help and we haven't even started talking about eliminating virtual adapters. Same as the previous one this property was also of no help. Next two properties I checked were ConfigManagerErrorCode and NetConnectionStatus in hopes of finding disabled and disconnected adapters. If an adapter is enabled but disconnected the ConfigManagerErrorCode = 0 with different NetConnectionStatus. If the adapter is disabled it reports ConfigManagerErrorCode = 22. This looked like a win by using (ConfigManagerErrorCode=0 or ConfigManagerErrorCode=22) in our condition. This way we get enabled (connected and disconnected adapters). Problem with all of the above properties is that none of them filter out the virtual adapters installed by virtualization software like VMware and VirtualBox. The last property to give hope is PNPDeviceID. There's an interesting observation about physical and virtual adapters with this property. Every virtual adapter PNPDeviceID starts with "ROOT\". Even VMware and VirtualBox ones. There were some really, really old physical adapters that had PNPDeviceID starting with "ROOT\" but those were in pre win XP era AFAIK. Since my minimum system to check was Windows XP SP2 I didn't have to worry about those. The only virtual adapter I've seen to not have PNPDeviceID start with "ROOT\" is the RAS Async Adapter for Wide Area Network. But because it is made by Microsoft we've eliminated it with the first condition for the manufacturer. Using the PNPDeviceID has so far proven to be really effective and I've tested it on over 20 different computers of various configurations from Windows XP laptops with wireless and bluetooth cards to virtualized Windows 2008 R2 servers. So far it always worked as expected. I will appreciate you letting me know if you find a configuration where it doesn't work. Let's see some C# code how to do this: ManagementObjectSearcher mos = null;// WHERE Manufacturer!='Microsoft' removes all of the // Microsoft provided virtual adapters like tunneling, miniports, and Wide Area Network adapters.mos = new ManagementObjectSearcher(@"SELECT * FROM Win32_NetworkAdapter WHERE Manufacturer != 'Microsoft'");// Trying the ConfigManagerErrorCode and NetConnectionStatus variations // proved to still not be enough and it returns adapters installed by // the virtualization software like VMWare and VirtualBox// ConfigManagerErrorCode = 0 -> Device is working properly. This covers enabled and/or disconnected devices// ConfigManagerErrorCode = 22 AND NetConnectionStatus = 0 -> Device is disabled and Disconnected. // Some virtual devices report ConfigManagerErrorCode = 22 (disabled) and some other NetConnectionStatus than 0mos = new ManagementObjectSearcher(@"SELECT * FROM Win32_NetworkAdapter WHERE Manufacturer != 'Microsoft' AND (ConfigManagerErrorCode = 0 OR (ConfigManagerErrorCode = 22 AND NetConnectionStatus = 0))");// Final solution with filtering on the Manufacturer and PNPDeviceID not starting with "ROOT\"// Physical devices have PNPDeviceID starting with "PCI\" or something else besides "ROOT\"mos = new ManagementObjectSearcher(@"SELECT * FROM Win32_NetworkAdapter WHERE Manufacturer != 'Microsoft' AND NOT PNPDeviceID LIKE 'ROOT\\%'");// Get the physical adapters and sort them by their index. // This is needed because they're not sorted by defaultIList<ManagementObject> managementObjectList = mos.Get() .Cast<ManagementObject>() .OrderBy(p => Convert.ToUInt32(p.Properties["Index"].Value)) .ToList();// Let's just show all the properties for all physical adapters.foreach (ManagementObject mo in managementObjectList){ foreach (PropertyData pd in mo.Properties) Console.WriteLine(pd.Name + ": " + (pd.Value ?? "N/A"));}   That's it. Hope this helps you in some way.

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  • SQL SERVER – Script to Find First Day of Current Month

    - by Pinal Dave
    Earlier I wrote a blog post about SQL SERVER – Query to Find First and Last Day of Current Month and it is a very popular post. In this post, I convert the datetime to Varchar and later on use it. However, SQL Expert Michael Usov has made a good point suggesting that it is not always a good idea to convert datetime to any other date format as it is quite possible that we may need it the value in the datetime format for other operation. He has suggested a very quick solution where we can get the first day of the current month with or without time value and keep them with datatype datetime. Here is the simple script for the same. -- first day of month -- with time zeroed out SELECT CAST(DATEADD(DAY,-DAY(GETDATE())+1, CAST(GETDATE() AS DATE)) AS DATETIME) -- with time as it was SELECT DATEADD(DAY,-DAY(GETDATE())+1, CAST(GETDATE() AS DATETIME)) Here is the resultset: Reference: Pinal Dave (http://blog.SQLAuthority.com)Filed under: PostADay, SQL, SQL Authority, SQL DateTime, SQL Function, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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  • SQL SERVER – The Story of a Lesser Known Startup Parameter in SQL Server – Guest Post by Balmukund Lakhani

    - by Pinal Dave
    This is a fantastic blog post from my dear friend Balmukund ( blog | twitter | facebook ). He had presented a fantastic session in our last UG and there were lots of requests from attendees that he blogs about it. Well, here is the blog post about the same very popular UG session. Let us read the entire blog post in the voice of the Balmukund himself. During my last session in SQL Bangalore User Group (Facebook) meeting, I was lucky enough to deliver a session on SQL Server Startup issue. The name of the session was “SQL Engine Starting Trouble – How to start?” From the feedback, I realized that one of the “not well known” startup parameter is “-m”. Okay, you might say “I know that this is used to start the SQL in single user mode”. But what you might not know is that you can pass a string with -m which has special meaning and use. I have used this parameter in my blog here but looks like not many of you have seen that. It happens most of the time when we want to start SQL Server in single user mode, someone else makes connection before you can. The only choice you have is to repeat same process again till you succeed. Some smart DBAs may disable the remote network protocols (TCP/IP and Named Pipes) of SQL Instance and allow only local connections to SQL. Once the activity is complete, our dear smart DBA has to remember to re-enable network protocols. Sometimes, it may be a local service or application getting connection to SQL before we can. There is a better way to deal with it. Yes, you have guessed it correctly: -m parameter which a string. Since I work with SQL Product Support team, I may know little more undocumented commands and parameters, but this is not an undocumented stuff. It’s already documented in books online. So in this blog, I am going to show a demo of its usage. As documentation shows, “Do not use this option as a security feature.” So please read this blog as knowledge enhancer and troubleshooting issues not security feature. In my laptop, I have a default instance of SQL Server 2012 and here is what we would in the configuration manager. Now, I would go ahead and stop SQL Service by selecting SQL Server (MSSQLServer) > Right Click > Stop. There are multiple ways to start SQL with startup parameter. 1) Use Net Start Command from command prompt Net Start MSSQLServer /mSQLCMD The above command is the simplest way to add startup parameter to SQL. This parameter would be cleared once we stop and start SQL. 2) Add Startup Parameter via configuration manager. Step is already listed here. We need to add -mSQLCMD If we compare 1 and 2, it’s clear that unless we modify startup parameter and remove -m, it would be in effect. 3) Start SQL Service via command line SQLServr.exe –mSQLCMD –s<InstanceName> Wait, what does SQLCMD mean with /m? It’s the instruction to SQL that start SQL Server in Single User Mode and allow only the application which is SQLCMD. Any other application would fail with Login Failed for User Error message. It would be important to note that string is case sensitive. This value should be picked up from application_name column from sys.dm_exec_sessions. I have made a connection using SQLCMD and as we can see it comes as upper case “SQLCMD”. If we want only management studio query windows to connect then we need to give -m” Microsoft SQL Server Management Studio – Query” as startup parameter. In below example, I have given it as SQLCMd (lower case d at the end) and we would notice that we would not be able to connect to SQL Instance. Above proves that parameter works as expected and it’s case sensitive. Error Log would show below information. How to get error log location? I have already blogged about it. Hope you have learned something new. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL, Technology

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  • Thunderbird uses the wrong browser

    - by Aaron Digulla
    I'm unable to make Thunderbird open the default browser. In the browser preferences, Chromium is selected as the default browser. It's also selected in "Default Applications" in System Settings. In Thunderbird, I read "Chrome (Default)" which is wrong on all levels: Chrome itself complains that it's not the default browser when I click a link inside Thunderbird. In all other places, that I could find, Chromium is the default Here is what I tried: I used update-alternatives --config x-www-browser to select chromium-browser as well (see How do I change the default browser?). And even when I select a different browser from the list in the Thunderbird preferences, it still opens Chrome. My current solution is to create a link from /usr/bin/google-chrome to chromium-browser. How can I force Thunderbird to use the browser I want??? EDIT I also updated gnome-www-browser (update-alternatives --config gnome-www-browser) after feedback from roadmr but that didn't help. At least sensible-browser opens Chromium, now, but Thunderbird is stubborn.

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  • Working with Joins in LINQ

    - by vik20000in
    While working with data most of the time we have to work with relation between different lists of data. Many a times we want to fetch data from both the list at once. This requires us to make different kind of joins between the lists of data. LINQ support different kinds of join Inner Join     List<Customer> customers = GetCustomerList();     List<Supplier> suppliers = GetSupplierList();      var custSupJoin =         from sup in suppliers         join cust in customers on sup.Country equals cust.Country         select new { Country = sup.Country, SupplierName = sup.SupplierName, CustomerName = cust.CompanyName }; Group Join – where By the joined dataset is also grouped.     List<Customer> customers = GetCustomerList();     List<Supplier> suppliers = GetSupplierList();      var custSupQuery =         from sup in suppliers         join cust in customers on sup.Country equals cust.Country into cs         select new { Key = sup.Country, Items = cs }; We can also work with the Left outer join in LINQ like this.     List<Customer> customers = GetCustomerList();     List<Supplier> suppliers = GetSupplierList();      var supplierCusts =         from sup in suppliers         join cust in customers on sup.Country equals cust.Country into cs         from c in cs.DefaultIfEmpty()  // DefaultIfEmpty preserves left-hand elements that have no matches on the right side         orderby sup.SupplierName         select new { Country = sup.Country, CompanyName = c == null ? "(No customers)" : c.CompanyName,                      SupplierName = sup.SupplierName};Vikram

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  • Recover that Photo, Picture or File You Deleted Accidentally

    - by The Geek
    Have you ever accidentally deleted a photo on your camera, computer, USB drive, or anywhere else? What you might not know is that you can usually restore those pictures—even from your camera’s memory stick. Windows tries to prevent you from making a big mistake by providing the Recycle Bin, where deleted files hang around for a while—but unfortunately it doesn’t work for external USB drives, USB flash drives, memory sticks, or mapped drives. The great news is that this technique also works if you accidentally deleted the photo… from the camera itself. That’s what happened to me, and prompted writing this article. Restore that File or Photo using Recuva The first piece of software that you’ll want to try is called Recuva, and it’s extremely easy to use—just make sure when you are installing it, that you don’t accidentally install that stupid Yahoo! toolbar that nobody wants. Now that you’ve installed the software, and avoided an awful toolbar installation, launch the Recuva wizard and let’s start through the process of recovering those pictures you shouldn’t have deleted. The first step on the wizard page will let you tell Recuva to only search for a specific type of file, which can save a lot of time while searching, and make it easier to find what you are looking for. Next you’ll need to specify where the file was, which will obviously be up to wherever you deleted it from. Since I deleted mine from my camera’s SD card, that’s where I’m looking for it. The next page will ask you whether you want to do a Deep Scan. My recommendation is to not select this for the first scan, because usually the quick scan can find it. You can always go back and run a deep scan a second time. And now, you’ll see all of the pictures deleted from your drive, memory stick, SD card, or wherever you searched. Looks like what happened in Vegas didn’t stay in Vegas after all… If there are a really large number of results, and you know exactly when the file was created or modified, you can switch to the advanced view, where you can sort by the last modified time. This can help speed up the process quite a bit, so you don’t have to look through quite as many files. At this point, you can right-click on any filename, and choose to Recover it, and then save the files elsewhere on your drive. Awesome! Restore that File or Photo using DiskDigger If you don’t have any luck with Recuva, you can always try out DiskDigger, another excellent piece of software. I’ve tested both of these applications very thoroughly, and found that neither of them will always find the same files, so it’s best to have both of them in your toolkit. Note that DiskDigger doesn’t require installation, making it a really great tool to throw on your PC repair Flash drive. Start off by choosing the drive you want to recover from…   Now you can choose whether to do a deep scan, or a really deep scan. Just like with Recuva, you’ll probably want to select the first one first. I’ve also had much better luck with the regular scan, rather than the “dig deeper” one. If you do choose the “dig deeper” one, you’ll be able to select exactly which types of files you are looking for, though again, you should use the regular scan first. Once you’ve come up with the results, you can click on the items on the left-hand side, and see a preview on the right.  You can select one or more files, and choose to restore them. It’s pretty simple! Download DiskDigger from dmitrybrant.com Download Recuva from piriform.com Good luck recovering your deleted files! And keep in mind, DiskDigger is a totally free donationware software from a single, helpful guy… so if his software helps you recover a photo you never thought you’d see again, you might want to think about throwing him a dollar or two. Similar Articles Productive Geek Tips Stupid Geek Tricks: Undo an Accidental Move or Delete With a Keyboard ShortcutRestore Accidentally Deleted Files with RecuvaCustomize Your Welcome Picture Choices in Windows VistaAutomatically Resize Picture Attachments in Outlook 2007Resize Your Photos with Easy Thumbnails TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 Icelandic Volcano Webcams Open Multiple Links At One Go NachoFoto Searches Images in Real-time Office 2010 Product Guides Google Maps Place marks – Pizza, Guns or Strip Clubs Monitor Applications With Kiwi

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  • Using the JRockit Flight Recorder as an Exception Profiler.

    - by Marcus Hirt
    There is a lot of new data points in the JRockit Flight Recorder compared to the data available in the old JRA. One set of data deals with exceptions and where they are thrown. In JRA, it was possible to tell how many exceptions were thrown, but it was not possible to determine from where they were thrown. Here is how to do a recording with exception profiling enabled from JRockit Mission Control. 1. Right click on the JVM to profile, select Start Flight Recording. 2. Select the Profiling with Exceptions template.   3. Wait for the recording to finish. The count down for the time left will show in the Flight Recorder Control view. 4. When done the recording will automatically be downloaded and displayed. To show the exceptions, go to the Code | Exceptions tab.

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  • Architecture strategies for a complex competition scoring system

    - by mikewassmer
    Competition description: There are about 10 teams competing against each other over a 6-week period. Each team's total score (out of a 1000 total available points) is based on the total of its scores in about 25,000 different scoring elements. Most scoring elements are worth a small fraction of a point and there will about 10 X 25,000 = 250,000 total raw input data points. The points for some scoring elements are awarded at frequent regular time intervals during the competition. The points for other scoring elements are awarded at either irregular time intervals or at just one moment in time. There are about 20 different types of scoring elements. Each of the 20 types of scoring elements has a different set of inputs, a different algorithm for calculating the earned score from the raw inputs, and a different number of total available points. The simplest algorithms require one input and one simple calculation. The most complex algorithms consist of hundreds or thousands of raw inputs and a more complicated calculation. Some types of raw inputs are automatically generated. Other types of raw inputs are manually entered. All raw inputs are subject to possible manual retroactive adjustments by competition officials. Primary requirements: The scoring system UI for competitors and other competition followers will show current and historical total team scores, team standings, team scores by scoring element, raw input data (at several levels of aggregation, e.g. daily, weekly, etc.), and other metrics. There will be charts, tables, and other widgets for displaying historical raw data inputs and scores. There will be a quasi-real-time dashboard that will show current scores and raw data inputs. Aggregate scores should be updated/refreshed whenever new raw data inputs arrive or existing raw data inputs are adjusted. There will be a "scorekeeper UI" for manually entering new inputs, manually adjusting existing inputs, and manually adjusting calculated scores. Decisions: Should the scoring calculations be performed on the database layer (T-SQL/SQL Server, in my case) or on the application layer (C#/ASP.NET MVC, in my case)? What are some recommended approaches for calculating updated total team scores whenever new raw inputs arrives? Calculating each of the teams' total scores from scratch every time a new input arrives will probably slow the system to a crawl. I've considered some kind of "diff" approach, but that approach may pose problems for ad-hoc queries and some aggegates. I'm trying draw some sports analogies, but it's tough because most games consist of no more than 20 or 30 scoring elements per game (I'm thinking of a high-scoring baseball game; football and soccer have fewer scoring events per game). Perhaps a financial balance sheet analogy makes more sense because financial "bottom line" calcs may be calculated from 250,000 or more transactions. Should I be making heavy use of caching for this application? Are there any obvious approaches or similar case studies that I may be overlooking?

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  • ASP.NET WebAPI Security 2: Identity Architecture

    - by Your DisplayName here!
    Pedro has beaten me to the punch with a detailed post (and diagram) about the WebAPI hosting architecture. So go read his post first, then come back so we can have a closer look at what that means for security. The first important takeaway is that WebAPI is hosting independent-  currently it ships with two host integration implementations – one for ASP.NET (aka web host) and WCF (aka self host). Pedro nicely shows the integration into the web host. Self hosting is not done yet so we will mainly focus on the web hosting case and I will point out security related differences when they exist. The interesting part for security (amongst other things of course) is the HttpControllerHandler (see Pedro’s diagram) – this is where the host specific representation of an HTTP request gets converted to the WebAPI abstraction (called HttpRequestMessage). The ConvertRequest method does the following: Create a new HttpRequestMessage. Copy URI, method and headers from the HttpContext. Copies HttpContext.User to the Properties<string, object> dictionary on the HttpRequestMessage. The key used for that can be found on HttpPropertyKeys.UserPrincipalKey (which resolves to “MS_UserPrincipal”). So the consequence is that WebAPI receives whatever IPrincipal has been set by the ASP.NET pipeline (in the web hosting case). Common questions are: Are there situations where is property does not get set? Not in ASP.NET – the DefaultAuthenticationModule in the HTTP pipeline makes sure HttpContext.User (and Thread.CurrentPrincipal – more on that later) are always set. Either to some authenticated user – or to an anonymous principal. This may be different in other hosting environments (again more on that later). Why so generic? Keep in mind that WebAPI is hosting independent and may run on a host that materializes identity completely different compared to ASP.NET (or .NET in general). This gives them a way to evolve the system in the future. How does WebAPI code retrieve the current client identity? HttpRequestMessage has an extension method called GetUserPrincipal() which returns the property as an IPrincipal. A quick look at self hosting shows that the moral equivalent of HttpControllerHandler.ConvertRequest() is HttpSelfHostServer.ProcessRequestContext(). Here the principal property gets only set when the host is configured for Windows authentication (inconsisteny). Do I like that? Well – yes and no. Here are my thoughts: I like that it is very straightforward to let WebAPI inherit the client identity context of the host. This might not always be what you want – think of an ASP.NET app that consists of UI and APIs – the UI might use Forms authentication, the APIs token based authentication. So it would be good if the two parts would live in a separate security world. It makes total sense to have this generic hand off point for identity between the host and WebAPI. It also makes total sense for WebAPI plumbing code (especially handlers) to use the WebAPI specific identity abstraction. But – c’mon we are running on .NET. And the way .NET represents identity is via IPrincipal/IIdentity. That’s what every .NET developer on this planet is used to. So I would like to see a User property of type IPrincipal on ApiController. I don’t like the fact that Thread.CurrentPrincipal is not populated. T.CP is a well established pattern as a one stop shop to retrieve client identity on .NET.  That makes a lot of sense – even if the name is misleading at best. There might be existing library code you want to call from WebAPI that makes use of T.CP (e.g. PrincipalPermission, or a simple .Name or .IsInRole()). Having the client identity as an ambient property is useful for code that does not have access to the current HTTP request (for calling GetUserPrincipal()). I don’t like the fact that that the client identity conversion from host to WebAPI is inconsistent. This makes writing security plumbing code harder. I think the logic should always be: If the host has a client identity representation, copy it. If not, set an anonymous principal on the request message. Btw – please don’t annoy me with the “but T.CP is static, and static is bad for testing” chant. T.CP is a getter/setter and, in fact I find it beneficial to be able to set different security contexts in unit tests before calling in some logic. And, in case you have wondered – T.CP is indeed thread static (and the name comes from a time where a logical operation was bound to a thread – which is not true anymore). But all thread creation APIs in .NET actually copy T.CP to the new thread they create. This is the case since .NET 2.0 and is certainly an improvement compared to how Win32 does things. So to sum it up: The host plumbing copies the host client identity to WebAPI (this is not perfect yet, but will surely be improved). or in other words: The current WebAPI bits don’t ship with any authentication plumbing, but solely use whatever authentication (and thus client identity) is set up by the host. WebAPI developers can retrieve the client identity from the HttpRequestMessage. Hopefully my proposed changes around T.CP and the User property on ApiController will be added. In the next post, I will detail how to add WebAPI specific authentication support, e.g. for Basic Authentication and tokens. This includes integrating the notion of claims based identity. After that we will look at the built-in authorization bits and how to improve them as well. Stay tuned.

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  • Reset the controls within asp placeholder

    - by alaa9jo
    I use placeholders very much in many projects,but in one of the projects I was asked to reset the controls within a specific placeholder to their original state after the user has finished from inserting his/her data. As everyone of us know,to keep the controls within a placeholder from disappearing after postbacks you have to recreate them,we add such a code in i.e. page_load,the controls will be recreated and their values will be loaded from viewstate (for some of them like textbox,checkboxs,..etc) automatically,that placeholder contains only textboxs so what I need is to block/ loading/clear that viewstate after inserting the data. First thought: Customizing placeholder I thought about it and tried overriding many methods but no success at all...maybe I'm missing something not sure. Second thought: recreate the controls 2 times: In page_load,I recreate the controls within that placeholder then in button click (the button that saves user's data) I recreate them once more and it worked! I just thought of sharing my experience in that case with everyone in case anyone needed it,any better suggestion(s) is welcomed.

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  • Check Your Spelling, Grammar, and Style in Firefox and Chrome

    - by Matthew Guay
    Are you tired of making simple writing mistakes that get past your browser’s spell-check?  Here’s how you can get advanced grammar check and more in Firefox and Chrome with After the Deadline. Microsoft Word has spoiled us with grammar, syntax, and spell checking, but the default spell check in Firefox and Chrome still only does basic checks.  Even webapps like Google Docs don’t check more than basic spelling errors.  However, WordPress.com is an exception; it offers advanced spelling, grammar, and syntax checking with its After the Deadline proofing system.  This helps you keep from making embarrassing mistakes on your blog posts, and now, thanks to a couple free browser plugins, it can help you keep from making these mistakes in any website or webapp. After the Deadline in Google Chrome Add the After the Deadline extension (link below) to Chrome as usual. As soon as it’s installed, you’re ready to start improving your online writing.  To check spelling, grammar, and more, click the ABC button that you’ll now see at the bottom of most text boxes online. After a quick scan, grammar mistakes are highlighted in green, complex expressions and other syntax problems are highlighted in blue, and spelling mistakes are highlighted in red as would be expected.  Click on an underlined word to choose one of its recommended changes or ignore the suggestion. Or, if you want more explanation about what was wrong with that word or phrase, click Explain for more info. And, if you forget to run an After the Deadline scan before submitting a text entry, it will automatically check to make sure you still want to submit it.  Click Cancel to go back and check your writing first.   To change the After the Deadline settings, click its icon in the toolbar and select View Options.  Additionally, if you want to disable it on the site you’re on, you can click Disable on this site directly from the popup. From the settings page, you can choose extra things to check for such as double negatives and redundant phrases, as well as add sites and words to ignore. After the Deadline in Firefox Add the After the Deadline add-on to Firefox (link below) as normal. After the Deadline basically the same in Firefox as it does in Chrome.  Select the ABC icon in the lower right corner of textboxes to check them for problems, and After the Deadline will underline the problems as it did in Chrome.  To view a suggested change in Firefox, right-click on the underlined word and select the recommended change or ignore the suggestion. And, if you forget to check, you’ll see a friendly reminder asking if you’re sure you want to submit your text like it is. You can access the After the Deadline settings in Firefox from the menu bar.  Click Tools, then select AtD Preferences.  In Firefox, the settings are in a options dialog with three tabs, but it includes the same options as the Chrome settings page.  Here you can make After the Deadline as correction-happy as you like.   Conclusion The web has increasingly become an interactive place, and seldom does a day go by that we aren’t entering text in forms and comments that may stay online forever.  Even our insignificant tweets are being archived in the Library of Congress.  After the Deadline can help you make sure that your permanent internet record is as grammatically correct as possible.  Even though it doesn’t catch every problem, and even misses some spelling mistakes, it’s still a great help. Links Download the After the Deadline extension for Google Chrome Download the After the Deadline add-on for Firefox Similar Articles Productive Geek Tips Quick Tip: Disable Favicons in FirefoxStupid Geek Tricks: Duplicate a Tab with a Shortcut Key in Chrome or FirefoxHow to Disable the New Geolocation Feature in Google ChromeStupid Geek Tricks: Compare Your Browser’s Memory Usage with Google ChromeStop YouTube Videos from Automatically Playing in Chrome TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips Acronis Online Backup DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows Easily Search Food Recipes With Recipe Chimp Tech Fanboys Field Guide Check these Awesome Chrome Add-ons iFixit Offers Gadget Repair Manuals Online Vista style sidebar for Windows 7 Create Nice Charts With These Web Based Tools

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  • Cannot resolve the collation conflict between "Latin1_General_CI_AS" and "SQL_Latin1_General_CP1_CI_

    - by Patrick Olurotimi Ige
    I was writing a store proc for a report and i needed some data from another server so i added a linked server to connect to this new db server. when i do a select like below its all fine select a,b,c from Server.DatabaseName.dbo.table But when i use the table in a join i get the error "Cannot resolve the collation conflict between "Latin1_General_CI_AS" and "SQL_Latin1_General_CP1_CI_AS" in the equal to operation." I did check the collation set on the 2 databases and it was actually the same and had mo idea why i'm getting the error. I later found out that you could specifically tell it to use a COLLATE Just rewrite your join like this on a.name COLLATE Latin1_General_CI_AS = eaobjname Hope that helps and saves your precious time Patrick

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  • Trace flags - TF 1117

    - by Damian
    I had a session about trace flags this year on the SQL Day 2014 conference that was held in Wroclaw at the end of April. The session topic is important to most of DBA's and the reason I did it was that I sometimes forget about various trace flags :). So I decided to prepare a presentation but I think it is a good idea to write posts about trace flags, too. Let's start then - today I will describe the TF 1117. I assume that we all know how to setup a TF using starting parameters or registry or in the session or on the query level. I will always write if a trace flag is local or global to make sure we know how to use it. Why do we need this trace flag? Let’s create a test database first. This is quite ordinary database as it has two data files (4 MB each) and a log file that has 1MB. The data files are able to expand by 1 MB and the log file grows by 10%: USE [master] GO CREATE DATABASE [TF1117]  ON  PRIMARY ( NAME = N'TF1117',      FILENAME = N'C:\Program Files\Microsoft SQL Server\MSSQL12.SQL2014\MSSQL\DATA\TF1117.mdf' ,      SIZE = 4096KB ,      MAXSIZE = UNLIMITED,      FILEGROWTH = 1024KB ), ( NAME = N'TF1117_1',      FILENAME = N'C:\Program Files\Microsoft SQL Server\MSSQL12.SQL2014\MSSQL\DATA\TF1117_1.ndf' ,      SIZE = 4096KB ,      MAXSIZE = UNLIMITED,      FILEGROWTH = 1024KB )  LOG ON ( NAME = N'TF1117_log',      FILENAME = N'C:\Program Files\Microsoft SQL Server\MSSQL12.SQL2014\MSSQL\DATA\TF1117_log.ldf' ,      SIZE = 1024KB ,      MAXSIZE = 2048GB ,      FILEGROWTH = 10% ) GO Without the TF 1117 turned on the data files don’t grow all up at once. When a first file is full the SQL Server expands it but the other file is not expanded until is full. Why is that so important? The SQL Server proportional fill algorithm will direct new extent allocations to the file with the most available space so new extents will be written to the file that was just expanded. When the TF 1117 is enabled it will cause all files to auto grow by their specified increment. That means all files will have the same percent of free space so we still have the benefit of evenly distributed IO. The TF 1117 is global flag so it affects all databases on the instance. Of course if a filegroup contains only one file the TF does not have any effect on it. Now let’s do a simple test. First let’s create a table in which every row will fit to a single page: The table definition is pretty simple as it has two integer columns and one character column of fixed size 8000 bytes: create table TF1117Tab (      col1 int,      col2 int,      col3 char (8000) ) go Now I load some data to the table to make sure that one of the data file must grow: declare @i int select @i = 1 while (@i < 800) begin       insert into TF1117Tab  values (@i, @i+1000, 'hello')        select @i= @i + 1 end I can check the actual file size in the sys.database_files DMV: SELECT name, (size*8)/1024 'Size in MB' FROM sys.database_files  GO   As you can see only the first data file was  expanded and the other has still the initial size:   name                  Size in MB --------------------- ----------- TF1117                5 TF1117_log            1 TF1117_1              4 There is also other methods of looking at the events of file autogrows. One possibility is to create an Extended Events session and the other is to look into the default trace file:     DECLARE @path NVARCHAR(260); SELECT    @path = REVERSE(SUBSTRING(REVERSE([path]),          CHARINDEX('\', REVERSE([path])), 260)) + N'log.trc' FROM    sys.traces WHERE   is_default = 1; SELECT    DatabaseName,                 [FileName],                 SPID,                 Duration,                 StartTime,                 EndTime,                 FileType =                         CASE EventClass                                     WHEN 92 THEN 'Data'                                    WHEN 93 THEN 'Log'             END FROM sys.fn_trace_gettable(@path, DEFAULT) WHERE   EventClass IN (92,93) AND StartTime >'2014-07-12' AND DatabaseName = N'TF1117' ORDER BY   StartTime DESC;   After running the query I can see the file was expanded and how long did the process take which might be useful from the performance perspective.    Now it’s time to turn on the flag 1117. DBCC TRACEON(1117)   I dropped the database and recreated it once again. Then I ran the queries and observed the results. After loading the records I see that both files were evenly expanded: name                  Size in MB --------------------- ----------- TF1117                5 TF1117_log            1 TF1117_1              5 I found also information in the default trace. The query returned three rows. The last one is connected to my first experiment when the TF was turned off.  The two rows shows that first file was expanded by 1MB and right after that operation the second file was expanded, too. This is what is this TF all about J  

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  • Windows Azure Evolution - Web Sites (aka Antares) Part 1

    - by Shaun
    This is the 3rd post of my Windows Azure Evolution series, focus on the new features and enhancement which was alone with the Windows Azure Platform Upgrade June 2012, announced at the MEET Windows Azure event on 7th June. In the first post I introduced the new preview developer portal and how to works for the existing features such as cloud services, storages and SQL databases. In the second one I talked about the Windows Azure .NET SDK 1.7 on the latest Visual Studio 2012 RC on Windows 8. From this one I will begin to introduce some new features. Now let’s have a look on the first one of them, Windows Azure Web Sites.   Overview Windows Azure Web Sites (WAWS), as known as Antares, was a new feature still in preview stage in this upgrade. It allows people to quickly and easily deploy websites to a highly scalable cloud environment, uses the languages and open source apps of the choice then deploy such as FTP, Git and TFS. It also can be integrated with Windows Azure services like SQL Database, Caching, CDN and Storage easily. After read its introduction we may have a question: since we can deploy a website from both cloud service web role and web site, what’s the different between them? So, let’s have a quick compare.   CLOUD SERVICE WEB SITE OS Windows Server Windows Server Virtualization Windows Azure Virtual Machine Windows Azure Virtual Machine Host IIS IIS Platform ASP.NET WebForm, ASP.NET MVC, WCF ASP.NET WebForm, ASP.NET MVC, PHP Language C#, VB.NET C#, VB.NET, PHP Database SQL Database SQL Database, MySQL Architecture Multi layered, background worker, message queuing, etc.. Simple website with backend database. VS Project Windows Azure Cloud Service ASP.NET Web Form, ASP.NET MVC, etc.. Out-of-box Gallery (none) Drupal, DotNetNuke, WordPress, etc.. Deployment Package upload, Visual Studio publish FTP, Git, TFS, WebMatrix Compute Mode Dedicate VM Shared Across VMs, Dedicate VM Scale Scale up, scale out Scale up, scale out As you can see, there are many difference between the cloud service and web site, but the main point is that, the cloud service focus on those complex architecture web application. For example, if you want to build a website with frontend layer, middle business layer and data access layer, with some background worker process connected through the message queue, then you should better use cloud service, since it provides full control of your code and application. But if you just want to build a personal blog or a  business portal, then you can use the web site. Since the web site have many galleries, you can create them even without any coding and configuration. David Pallmann have an awesome figure explains the benefits between the could service, web site and virtual machine.   Create a Personal Blog in Web Site from Gallery As I mentioned above, one of the big feature in WAWS is to build a website from an existing gallery, which means we don’t need to coding and configure. What we need to do is open the windows azure developer portal and click the NEW button, select WEB SITE and FROM GALLERY. In the popping up windows there are many websites we can choose to use. For example, for personal blog there are Orchard CMS, WordPress; for CMS there are DotNetNuke, Drupal 7, mojoPortal. Let’s select WordPress and click the next button. The next step is to configure the web site. We will need to specify the DNS name and select the subscription and region. Since the WordPress uses MySQL as its backend database, we also need to create a MySQL database as well. Windows Azure Web Sites utilize ClearDB to host the MySQL databases. You cannot create a MySQL database directly from SQL Databases section. Finally, since we selected to create a new MySQL database we need to specify the database name and region in the last step. Also we need to accept the ClearDB’s terms as well. Then windows azure platform will download the WordPress codes and deploy the MySQL database and website. Then it will be ready to use. Select the website and click the BROWSE button, the WordPress administration page will be shown. After configured the WordPress here is my personal web blog on the cloud. It took me no more than 10 minutes to establish without any coding.   Monitor, Configure, Scale and Linked Resources Let’s click into the website I had just created in the portal and have a look on what we can do. In the website details page where are five sections. - Dashboard The overall information about this website, such as the basic usage status, public URL, compute mode, FTP address, subscription and links that we can specify the deployment credentials, TFS and Git publish setting, etc.. - Monitor Some status information such as the CPU usage, memory usage etc., errors, etc.. We can add more metrics by clicking the ADD METRICS button and the bottom as well. - Configure Here we can set the configurations of our website such as the .NET and PHP runtime version, diagnostics settings, application settings and the IIS default documents. - Scale This is something interesting. In WAWS there are two compute mode or called web site mode. One is “shared”, which means our website will be shared with other web sites in a group of windows azure virtual machines. Each web site have its own process (w3wp.exe) with some sandbox technology to isolate from others. When we need to scaling-out our web site in shared mode, we actually increased the working process count. Hence in shared mode we cannot specify the virtual machine size since they are shared across all web sites. This is a little bit different than the scaling mode of the cloud service (hosted service web role and worker role). The other mode called “dedicate”, which means our web site will use the whole windows azure virtual machine. This is the same hosting behavior as cloud service web role. In web role it will be deployed on the virtual machines we specified and all of them are only used by us. In web sites dedicate mode, it’s the same. In this mode when we scaling-out our web site we will use more virtual machines, and each of them will only host our own website. And we can specify the virtual machine size in this mode. In the developer portal we can select which mode we are using from the scale section. In shared mode we can only specify the instance count, but in dedicate mode we can specify the instance size as well as the instance count. - Linked Resource The MySQL database created alone with the creation of our WordPress web site is a linked resource. We can add more linked resources in this section.   Pricing For the web site itself, since this feature is in preview period if you are using shared mode, then you will get free up to 10 web sites. But if you are using dedicate mode, the price would be the virtual machines you are using. For example, if you are using dedicate and configured two middle size virtual machines then you will pay $230.40 per month. If there is SQL Database linked to your web site then they will be charged separately based on the Pay-As-You-Go price. For example a 1GB web edition database costs $9.99 per month. And the bandwidth will be charged as well. For example 10GB outbound data transfer costs $1.20 per month. For more information about the pricing please have a look at the windows azure pricing page.   Summary Windows Azure Web Sites gives us easier and quicker way to create, develop and deploy website to window azure platform. Comparing with the cloud service web role, the WAWS have many out-of-box gallery we can use directly. So if you just want to build a blog, CMS or business portal you don’t need to learn ASP.NET, you don’t need to learn how to configure DotNetNuke, you don’t need to learn how to prepare PHP and MySQL. By using WAWS gallery you can establish a website within 10 minutes without any lines of code. But in some cases we do need to code by ourselves. We may need to tweak the layout of our pages, or we may have a traditional ASP.NET or PHP web application which needed to migrated to the cloud. Besides the gallery WAWS also provides many features to download, upload code. It also provides the feature to integrate with some version control services such as TFS and Git. And it also provides the deploy approaches through FTP and Web Deploy. In the next post I will demonstrate how to use WebMatrix to download and modify the website, and how to use TFS and Git to deploy automatically one our code changes committed.   Hope this helps, Shaun All documents and related graphics, codes are provided "AS IS" without warranty of any kind. Copyright © Shaun Ziyan Xu. This work is licensed under the Creative Commons License.

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  • Oracle ATG Web Commerce 10 Implementation Developer Boot Camp - Reading (UK) - October 1-12, 2012

    - by Richard Lefebvre
    REGISTER NOW: Oracle ATG Web Commerce 10 Implementation Developer Boot Camp Reading, UK, October 1-12, 2012! OPN invites you to join us for a 10-day implementation bootcamp on Oracle ATG Web Commerce in Reading, UK from October 1-12, 2012.This 10-day boot camp is designed to provide partners with hands-on experience and technical training to successfully build and deploy Oracle ATG Web Commerce 10 Applications. This particular boot camp is focused on helping partners develop the essential skills needed to implement every aspect of an ATG Commerce Application from scratch, (not CRS-based), with a specific goal of enabling experienced Java/J2EE developers with a path towards becoming functional, effective, and contributing members of an ATG implementation team. Built for both new and experienced ATG developers alike, the collaborative nature of this program and its exercises, have proven to be highly effective and extremely valuable in learning the best practices for implementing ATG solutions. Though not required, this bootcamp provides a structured path to earning a Certified Oracle ATG Web Commerce 10 Specialization! What Is Covered: This boot camp is for Application Developers and Software Architects wanting to gain valuable insight into ATG application development best practices, as well as relevant and applicable implementation experience on projects modeled after four of the most common types of applications built on the ATG platform. The following learning objectives are all critical, and are of equal priority in enabling this role to succeed. This learning boot camp will help with: Building a basic functional transaction-ready ATG Web Commerce 10 Application. Utilizing ATG’s platform features such as scenarios, slots, targeters, user profiles and segments, to create a personalized user experience. Building Nucleus components to support and/or extend application functionality. Understanding the intricacies of ATG order checkout and fulfillment. Specifying, designing and implementing new commerce features in ATG 10. Building a functional commerce application modeled after four of the most common types of applications built on the ATG platform, within an agile-based project team environment and under simulated real-world project conditions. Duration: The Oracle ATG Web Commerce 10 Implementation Developer Boot Camp is an instructor-led workshop spanning 10 days. Audience: Application Developers Software Architects Prerequisite Training and Environment Requirements: Programming and Markup Experience with Java J2EE, JavaScript, XML, HTML and CSS Completion of Oracle ATG Web Commerce 10 Implementation Specialist Development Guided Learning Path modules Participants will be required to bring their own laptop that meets the minimum specifications:   64-bit PC and OS (e.g. Windows 7 64-bit) 4GB RAM or more 40GB Hard Disk Space Laptops will require access to the Internet through Remote Desktop via Windows. Agenda Topics: Week 1 – Day 1 through 5 Build a Basic Commerce Application In week one of the boot camp training, we will apply knowledge learned from the ATG Web Commerce 10 Implementation Developer Guided Learning Path modules, towards building a basic transaction-ready commerce application. There will be little to no lectures delivered in this boot camp, as developers will be fully engaged in ATG Application Development activities and best practices. Developers will work independently on the following lab assignments from day's 1 through 5: Lab Assignments  1 Environment Setup 2 Build a dynamic Home Page 3 Site Authentication 4 Build Customer Registration 5 Display Top Level Categories 6 Display Product Sub-Categories 7 Display Product List Page 8 Display Product Detail Page 9 ATG Inventory 10 Build “Add to Cart” Functionality 11 Build Shopping Cart 12 Build Checkout Page  13 Build Checkout Review Page 14 Create an Order and Build Order Confirmation Page 15 Implement Slots and Targeters for Personalization 16 Implement Pricing and Promotions 17 Order Fulfillment Back to top Week 2 – Day 6 through 10 Team-based Case Project In the second week of the boot camp training, participants will be asked to join a project team that will select a case project for the team to implement. Teams will be able to choose from four of the most common application types developed and deployed on the ATG platform. They are as follows: Hard goods with physical fulfillment, Soft goods with electronic fulfillment, a Service or subscription case example, a Course/Event registration case example. Team projects will have approximately 160 hours of use cases/stories for each team to build (40 hours per developer). Each day's Use Cases/Stories will build upon the prior day's work, and therefore must be fully completed at the end of each day. Please note that this boot camp intends to simulate real-world project conditions, and as such will likely require the need for project teams to possibly work beyond normal business hours. To promote further collaboration and group learning, each team will be asked to present their work and share the methodologies and solutions that they've applied to their cases at the end of each day. Location: Oracle Reading CVC TPC510 Room: Wraysbury Reading, UK 9:00 AM – 5:00 PM  Registration Fee (10 Days): US $3,375 Please click on the following link to REGISTER or  visit the Oracle ATG Web Commerce 10 Implementation Developer Boot Camp page for more information. Questions: Patrick Ty Partner Enablement, Oracle Commerce Phone: 310.343.7687 Mobile: 310.633.1013 Email: [email protected]

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  • Joins in single-table queries

    - by Rob Farley
    Tables are only metadata. They don’t store data. I’ve written something about this before, but I want to take a viewpoint of this idea around the topic of joins, especially since it’s the topic for T-SQL Tuesday this month. Hosted this time by Sebastian Meine (@sqlity), who has a whole series on joins this month. Good for him – it’s a great topic. In that last post I discussed the fact that we write queries against tables, but that the engine turns it into a plan against indexes. My point wasn’t simply that a table is actually just a Clustered Index (or heap, which I consider just a special type of index), but that data access always happens against indexes – never tables – and we should be thinking about the indexes (specifically the non-clustered ones) when we write our queries. I described the scenario of looking up phone numbers, and how it never really occurs to us that there is a master list of phone numbers, because we think in terms of the useful non-clustered indexes that the phone companies provide us, but anyway – that’s not the point of this post. So a table is metadata. It stores information about the names of columns and their data types. Nullability, default values, constraints, triggers – these are all things that define the table, but the data isn’t stored in the table. The data that a table describes is stored in a heap or clustered index, but it goes further than this. All the useful data is going to live in non-clustered indexes. Remember this. It’s important. Stop thinking about tables, and start thinking about indexes. So let’s think about tables as indexes. This applies even in a world created by someone else, who doesn’t have the best indexes in mind for you. I’m sure you don’t need me to explain Covering Index bit – the fact that if you don’t have sufficient columns “included” in your index, your query plan will either have to do a Lookup, or else it’ll give up using your index and use one that does have everything it needs (even if that means scanning it). If you haven’t seen that before, drop me a line and I’ll run through it with you. Or go and read a post I did a long while ago about the maths involved in that decision. So – what I’m going to tell you is that a Lookup is a join. When I run SELECT CustomerID FROM Sales.SalesOrderHeader WHERE SalesPersonID = 285; against the AdventureWorks2012 get the following plan: I’m sure you can see the join. Don’t look in the query, it’s not there. But you should be able to see the join in the plan. It’s an Inner Join, implemented by a Nested Loop. It’s pulling data in from the Index Seek, and joining that to the results of a Key Lookup. It clearly is – the QO wouldn’t call it that if it wasn’t really one. It behaves exactly like any other Nested Loop (Inner Join) operator, pulling rows from one side and putting a request in from the other. You wouldn’t have a problem accepting it as a join if the query were slightly different, such as SELECT sod.OrderQty FROM Sales.SalesOrderHeader AS soh JOIN Sales.SalesOrderDetail as sod on sod.SalesOrderID = soh.SalesOrderID WHERE soh.SalesPersonID = 285; Amazingly similar, of course. This one is an explicit join, the first example was just as much a join, even thought you didn’t actually ask for one. You need to consider this when you’re thinking about your queries. But it gets more interesting. Consider this query: SELECT SalesOrderID FROM Sales.SalesOrderHeader WHERE SalesPersonID = 276 AND CustomerID = 29522; It doesn’t look like there’s a join here either, but look at the plan. That’s not some Lookup in action – that’s a proper Merge Join. The Query Optimizer has worked out that it can get the data it needs by looking in two separate indexes and then doing a Merge Join on the data that it gets. Both indexes used are ordered by the column that’s indexed (one on SalesPersonID, one on CustomerID), and then by the CIX key SalesOrderID. Just like when you seek in the phone book to Farley, the Farleys you have are ordered by FirstName, these seek operations return the data ordered by the next field. This order is SalesOrderID, even though you didn’t explicitly put that column in the index definition. The result is two datasets that are ordered by SalesOrderID, making them very mergeable. Another example is the simple query SELECT CustomerID FROM Sales.SalesOrderHeader WHERE SalesPersonID = 276; This one prefers a Hash Match to a standard lookup even! This isn’t just ordinary index intersection, this is something else again! Just like before, we could imagine it better with two whole tables, but we shouldn’t try to distinguish between joining two tables and joining two indexes. The Query Optimizer can see (using basic maths) that it’s worth doing these particular operations using these two less-than-ideal indexes (because of course, the best indexese would be on both columns – a composite such as (SalesPersonID, CustomerID – and it would have the SalesOrderID column as part of it as the CIX key still). You need to think like this too. Not in terms of excusing single-column indexes like the ones in AdventureWorks2012, but in terms of having a picture about how you’d like your queries to run. If you start to think about what data you need, where it’s coming from, and how it’s going to be used, then you will almost certainly write better queries. …and yes, this would include when you’re dealing with regular joins across multiples, not just against joins within single table queries.

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  • SQL SERVER – Selecting Domain from Email Address

    - by pinaldave
    Recently I came across a quick need where I needed to retrieve domain of the email address. The email address is in the database table. I quickly wrote following script which will extract the domain and will also count how many email addresses are there with the same domain address. SELECT RIGHT(Email, LEN(Email) - CHARINDEX('@', email)) Domain , COUNT(Email) EmailCount FROM   dbo.email WHERE  LEN(Email) > 0 GROUP BY RIGHT(Email, LEN(Email) - CHARINDEX('@', email)) ORDER BY EmailCount DESC Above script will select the domain after @ character. Please note, if there is more than one @ character in the email, this script will not work as that email address is already invalid. Do you have any similar script which can do the same thing efficiently? Please post as a comment. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – Number-Crunching with SQL Server – Exceed the Functionality of Excel

    - by Pinal Dave
    Imagine this. Your users have developed an Excel spreadsheet that extracts data from your SQL Server database, manipulates that data through the use of Excel formulas and, possibly, some VBA code which is then used to calculate P&L, hedging requirements or even risk numbers. Management comes to you and tells you that they need to get rid of the spreadsheet and that the results of the spreadsheet calculations need to be persisted on the database. SQL Server has a very small set of functions for analyzing data. Excel has hundreds of functions for analyzing data, with many of them focused on specific financial and statistical calculations. Is it even remotely possible that you can use SQL Server to replace the complex calculations being done in a spreadsheet? Westclintech has developed a library of functions that match or exceed the functionality of Excel’s functions and contains many functions that are not available in EXCEL. Their XLeratorDB library of functions contains over 700 functions that can be incorporated into T-SQL statements. XLeratorDB takes advantage of the SQL CLR architecture introduced in SQL Server 2005. SQL CLR permits managed code to be compiled into the database and run alongside built-in SQL Server functions like COUNT or SUM. The Westclintech developers have taken advantage of this architecture to bring robust analytical functions to the database. In our hypothetical spreadsheet, let’s assume that our users are using the YIELD function and that the data are extracted from a table in our database called BONDS. Here’s what the spreadsheet might look like. We go to column G and see that it contains the following formula. Obviously, SQL Server does not offer a native YIELD function. However, with XLeratorDB we can replicate this calculation in SQL Server with the following statement: SELECT *, wct.YIELD(CAST(GETDATE() AS date),Maturity,Rate,Price,100,Frequency,Basis) AS YIELD FROM BONDS This produces the following result. This illustrates one of the best features about XLeratorDB; it is so easy to use. Since I knew that the spreadsheet was using the YIELD function I could use the same function with the same calling structure to do the calculation in SQL Server. I didn’t need to know anything at all about the mechanics of calculating the yield on a bond. It was pretty close to cut and paste. In fact, that’s one way to construct the SQL. Just copy the function call from the cell in the spreadsheet and paste it into SMS and change the cell references to column names. I built the SQL for this query by starting with this. SELECT * ,YIELD(TODAY(),B2,C2,D2,100,E2,F2) FROM BONDS I then changed the cell references to column names. SELECT * --,YIELD(TODAY(),B2,C2,D2,100,E2,F2) ,YIELD(TODAY(),Maturity,Rate,Price,100,Frequency,Basis) FROM BONDS Finally, I replicated the TODAY() function using GETDATE() and added the schema name to the function name. SELECT * --,YIELD(TODAY(),B2,C2,D2,100,E2,F2) --,YIELD(TODAY(),Maturity,Rate,Price,100,Frequency,Basis) ,wct.YIELD(GETDATE(),Maturity,Rate,Price,100,Frequency,Basis) FROM BONDS Then I am able to execute the statement returning the results seen above. The XLeratorDB libraries are heavy on financial, statistical, and mathematical functions. Where there is an analog to an Excel function, the XLeratorDB function uses the same naming conventions and calling structure as the Excel function, but there are also hundreds of additional functions for SQL Server that are not found in Excel. You can find the functions by opening Object Explorer in SQL Server Management Studio (SSMS) and expanding the Programmability folder under the database where the functions have been installed. The  Functions folder expands to show 3 sub-folders: Table-valued Functions; Scalar-valued functions, Aggregate Functions, and System Functions. You can expand any of the first three folders to see the XLeratorDB functions. Since the wct.YIELD function is a scalar function, we will open the Scalar-valued Functions folder, scroll down to the wct.YIELD function and and click the plus sign (+) to display the input parameters. The functions are also Intellisense-enabled, with the input parameters displayed directly in the query tab. The Westclintech website contains documentation for all the functions including examples that can be copied directly into a query window and executed. There are also more one hundred articles on the site which go into more detail about how some of the functions work and demonstrate some of the extensive business processes that can be done in SQL Server using XLeratorDB functions and some T-SQL. XLeratorDB is organized into libraries: finance, statistics; math; strings; engineering; and financial options. There is also a windowing library for SQL Server 2005, 2008, and 2012 which provides functions for calculating things like running and moving averages (which were introduced in SQL Server 2012), FIFO inventory calculations, financial ratios and more, without having to use triangular joins. To get started you can download the XLeratorDB 15-day free trial from the Westclintech web site. It is a fully-functioning, unrestricted version of the software. If you need more than 15 days to evaluate the software, you can simply download another 15-day free trial. XLeratorDB is an easy and cost-effective way to start adding sophisticated data analysis to your SQL Server database without having to know anything more than T-SQL. Get XLeratorDB Today and Now! Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL Tagged: Excel

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  • When to use HTTP status code 404 in an API

    - by Sybiam
    I am working on a project and after arguing with people at work for about more than a hour. I decided to know what people on stack-exchange might say. We're writing an API for a system, there is a query that should return a tree of Organization or a tree of Goals. The tree of Organization is the organization in which the user is present, In other words, this tree should always exists. In the organization, a tree of goal should be always present. (that's where the argument started). In case where the tree doesn't exist, my co-worker decided that it would be right to answer response with status code 200. And then started asking me to fix my code because the application was falling apart when there is no tree. I'll try to spare flames and fury. I suggested to raise a 404 error when there is no tree. It would at least let me know that something is wrong. When using 200, I have to add special check to my response in the success callback to handle errors. I'm expecting to receive an object, but I may actually receive an empty response because nothing is found. It sounds totally fair to mark the response as a 404. And then war started and I got the message that I didn't understand HTTP status code schema. So I'm here and asking what's wrong with 404 in this case? I even got the argument "It found nothing, so it's right to return 200". I believe that it's wrong since the tree should be always present. If we found nothing and we are expecting something, it should be a 404. More info, I forgot to add the urls that are fetched. Organizations /OrgTree/Get Goals /GoalTree/GetByDate?versionDate=... /GoalTree/GetById?versionId=... My mistake, both parameters are required. If any versionDate that can be parsed to a date is provided, it will return the closes revision. If you enter something in the past, it will return the first revision. If by Id with a id that doesn't exists, I suspect it's going to return an empty response with 200. Extra Also, I believe the best answer to the problem is to create default objects when organizations are created, having no tree shouldn't be a valid case and should be seen as an undefined behavior. There is no way an account can be used without both trees. For that reasons, they should be always present. also I got linked this (one similar but I can't find it) http://viswaug.files.wordpress.com/2008/11/http-headers-status1.png

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