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• SQL SERVER – Rename Columnname or Tablename – SQL in Sixty Seconds #032 – Video

  - by pinaldave

  We all make mistakes at some point of time and we all change our opinion. There are quite a lot of people in the world who have changed their name after they have grown up. Some corrected their parent’s mistake and some create new mistake. Well, databases are not protected from such incidents. There are many reasons why developers may want to change the name of the column or table after it was initially created. The goal of this video is not to dwell on the reasons but to learn how we can rename the column and table. Earlier I have written the article on this subject over here: SQL SERVER – How to Rename a Column Name or Table Name. I have revised the same article over here and created this video. There is one very important point to remember that by changing the column name or table name one creates the possibility of errors in the application the columns and tables are used. When any column or table name is changed, the developer should go through every place in the code base, ad-hoc queries, stored procedures, views and any other place where there are possibility of their usage and change them to the new name. If this is one followed up religiously there are quite a lot of changes that application will stop working due to this name change.  One has to remember that changing column name does not change the name of the indexes, constraints etc and they will continue to reference the old name. Though this will not stop the show but will create visual un-comfort as well confusion in many cases. Here is my question back to you – have you changed ever column name or table name in production database (after project going live)? If yes, what was the scenario and need of doing it. After all it is just a name. Let me know what you think of this video. Here is the updated script. USE tempdb GO CREATE TABLE TestTable (ID INT, OldName VARCHAR(20)) GO INSERT INTO TestTable VALUES (1, 'First') GO -- Check the Tabledata SELECT * FROM TestTable GO -- Rename the ColumnName sp_RENAME 'TestTable.OldName', 'NewName', 'Column' GO -- Check the Tabledata SELECT * FROM TestTable GO -- Rename the TableName sp_RENAME 'TestTable', 'NewTable' GO -- Check the Tabledata - Error SELECT * FROM TestTable GO -- Check the Tabledata - New SELECT * FROM NewTable GO -- Cleanup DROP TABLE NewTable GO Related Tips in SQL in Sixty Seconds: SQL SERVER – How to Rename a Column Name or Table Name What would you like to see in the next SQL in Sixty Seconds video? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Database, Pinal Dave, PostADay, SQL, SQL Authority, SQL in Sixty Seconds, SQL Query, SQL Scripts, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL, Technology, Video Tagged: Excel

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• CodePlex Daily Summary for Sunday, December 19, 2010

  CodePlex Daily Summary for Sunday, December 19, 2010Popular ReleasesTeam Foundation Server Administration Tool: 2.1: TFS Administration Tool 2.1, is the first version of the TFS Administration Tool which is built on top of the Team Foundation Server 2010 object model. TFS Administration Tool 2.1 can be installed on machines that are running either Team Explorer 2010, or Team Foundation Server 2010.SQL Monitor: SQL Monitor 3.0 alpha 5: 1. fix a problem with not expanding nodes in object explorer, sorryHacker Passwords: HackerPasswords.zip: Source code, executable and documentationWatchersNET.SiteMap: WatchersNET.SiteMap 01.03.03: Whats NewSkin Object: You can now filter by Terms for Example use: <object id="dnnSITEMAPSL" codetype="dotnetnuke/server" codebase="SITEMAPSL"> <param name="TaxMode" value="terms" /> <param name="TaxTerms" value="TermName1,TermName2" /> </object> changes Tax Term Filter should work correct nowSubtitleTools: SubtitleTools 1.3: - Added .srt FileAssociation & Win7 ShowRecentCategory feature. - Applied UnifiedYeKe to fix Persian search problems. - Reduced file size of Persian subtitles for uploading @OSDB.EnhSim: EnhSim 2.2.3 ALPHA: 2.2.3 ALPHAThis release adds in the changes for 4.03a at level 85 To use this release, you must have the Microsoft Visual C++ 2010 Redistributable Package installed. This can be downloaded from http://www.microsoft.com/downloads/en/details.aspx?FamilyID=A7B7A05E-6DE6-4D3A-A423-37BF0912DB84 To use the GUI you must have the .NET 4.0 Framework installed. This can be downloaded from http://www.microsoft.com/downloads/en/details.aspx?FamilyID=9cfb2d51-5ff4-4491-b0e5-b386f32c0992 - Added in th...Facebook C# SDK: 4.1.0: - Lots of bug fixes - Removed Dynamic Runtime Language dependencies from non-dynamic platforms. - Samples included in release for ASP.NET, MVC, Silverlight, Windows Phone 7, WPF, WinForms, and one Visual Basic Sample - Changed internal serialization to use Json.net - BREAKING CHANGE: Canvas Session is no longer support. Use Signed Request instead. Canvas Session has been deprecated by Facebook. - BREAKING CHANGE: Some renames and changes with Authorizer, CanvasAuthorizer, and Authorization ac...NuGet (formerly NuPack): NuGet 1.0 build 11217.102: Note: this release is slightly newer than RC1, and fixes a couple issues relating to updating packages to newer versions. NuGet is a free, open source developer focused package management system for the .NET platform intent on simplifying the process of incorporating third party libraries into a .NET application during development. This release is a Visual Studio 2010 extension and contains the the Package Manager Console and the Add Package Dialog. This new build targets the newer feed (h...WCF Community Site: WCF Web APIs 10.12.17: Welcome to the second release of WCF Web APIs on codeplex Here is what is new in this release. WCF Support for jQuery - create WCF web services that are easy to consume from JavaScript clients, in particular jQuery. Better support for using JsonValue as dynamic Support for JsonValue change notification events for databinding and other purposes Support for going between JsonValue and CLR types WCF HTTP - create HTTP / REST based web services. This is a minor release which contains fixe...Orchard Project: Orchard 0.9: Orchard Release Notes Build: 0.9.253 Published: 12/16/2010 How to Install OrchardTo install the Orchard tech preview using Web PI, follow these instructions: http://www.orchardproject.net/docs/Installing-Orchard-Using-Web-PI.ashx Web PI will detect your hardware environment and install the application. --OR-- Alternatively, to install the release manually, download the Orchard.Web.0.9.253.zip file. The zip contents are pre-built and ready-to-run. Simply extract the contents of the Orch...Pyxis 2: Beta 2.2: An issue stopping the Checkbox from working properly has been resolved (gradient background has also been added) A TabDialog control has been added NumericUpDown control added A driver for the VS1053 has been added (not yet in use) PyxisAPI.OpenFile now works with all its features PyxisAPI.SaveFile now works with all features Settings window is now available from the Pyxis menu You can now connect using Static IP or DHCP You can now set your system time from the Settings windo...sgMotion Animation Library: sgMotion v1.3 for SunBurn 2.0.9 [Includes Sample]: sgMotion 1.3 release for use with SunBurn 2.0.9 (all editions). Includes example project with assets, and full Windows and Xbox support. (tested on all platforms)DotSpatial: DotSpatial 12-15-2010: This release contains a few minor bug fixes and hopefully the GDAL libraries for the 3.5 x86 build actually built to the correct directory this time.DotNetNuke® Community Edition: 05.06.01 Beta: This is the initial Beta of DotNetNuke 5.6.1. See the DotNetNuke Roadmap a full list of changes in this release.MSBuild Extension Pack: December 2010: Release Blog Post The MSBuild Extension Pack December 2010 release provides a collection of over 380 MSBuild tasks. A high level summary of what the tasks currently cover includes the following: System Items: Active Directory, Certificates, COM+, Console, Date and Time, Drives, Environment Variables, Event Logs, Files and Folders, FTP, GAC, Network, Performance Counters, Registry, Services, Sound Code: Assemblies, AsyncExec, CAB Files, Code Signing, DynamicExecute, File Detokenisation, GU...TweetSharp: TweetSharp v2.0.0.0 - Preview 5: Documentation for this release may be found at http://tweetsharp.codeplex.com/wikipage?title=UserGuide&referringTitle=Documentation. Note: This code is currently preview quality. Preview 5 ChangesMaintenance release with user reported fixes Preview 4 ChangesReintroduced fluent interface support via satellite assembly Added entities support, entity segmentation, and ITweetable/ITweeter interfaces for client development Numerous fixes reported by preview users Preview 3 ChangesNumerous ...Silverlight Contrib: Silverlight Contrib 2010.1.0: 2010.1.0 New FeaturesCompatibility Release for Silverlight 4 and Visual Studio 2010FlickrNet API Library: 3.1.4000: Newest release. Now contains dedicated Windows Phone 7 DLL as well as all previous DLLs. Also contains Windows Help file documentation now as standard.mojoPortal: 2.3.5.8: see release notes on mojoportal.com http://www.mojoportal.com/mojoportal-2358-released.aspx Note that we have separate deployment packages for .NET 3.5 and .NET 4.0 The deployment package downloads on this page are pre-compiled and ready for production deployment, they contain no C# source code. To download the source code see the Source Code Tab I recommend getting the latest source code using TortoiseHG, you can get the source code corresponding to this release here.Microsoft All-In-One Code Framework: Visual Studio 2010 Code Samples 2010-12-13: Code samples for Visual Studio 2010New ProjectsANLP - Another .NET Lexer Parser: This project aims to have a lexer/parser working in Silverlight and help people to write their own grammar and make the lexer/parser available in Silverlight.Better App Tab Shortcuts Firefox Extension: An extension for Firefox 4.0 which improves the shortcuts for selecting tabs.BizTalk Map Converter: Converts BizTalk Maps into ExcelCampo Minado: Campo minado em SilverlightCSharpHASH: Hash project is an college project conserning business software development. Written in C#.DS_HW1: hw1DynamicViewModel: MVVM using POCOs with .NET 4.0: This project aims to provide a way to implement the Model View ViewModel (MVVM) architectural pattern using Plain Old CLR Objects (POCOs) while taking full advantage of .NET 4.0 DynamicObject Class.Evolution Game: Evolution game that uses genetic algorithms to visualize life of different species.Fluent Parser: Fluent Parser is a library allowing to build a syntaxic analyser in C#. The grammar is built using only .NET objects into the form of a Parsing Expression Grammar (PEG).GoogleMusic Player: Choose and play music from newly launched google Music http://www.google.co.in/music create and save playlists Using C#Gracefully update SharePoint 2010 document metadata: Users want to update the metadata for a document in a document library, for which they don’t have access or if they wanted to update some read-only fields. Hacker Passwords: Hacker Passwords generator - free open sourceHTML5 Canvas FlowView: FlowView is a simple to use API for creating/implementing a flowview style element in HTML5/Canvas. The FlowView looks much like something from Apple's cover view.L#: A F# program to provide similar functionalities offered by Prolog for F# oriented applications.MapInfo Tools: Utilities for working with MapInfo files.Notepad X: Notepad X is an alternative open source text editor for Microsoft Windows, with a lot of customization options created to help users managing text documents, featuring tab navigation.OpenFlyClient: An educational open source of a client written in C# for FlyFF. This is for educational and evaluation purposes only. Using this for private servers is not allowed.Orkut API Library: Orkut API Library (more of a wrapper) for .NET makes it easier for .NET developers creating web and/or desktop applications to leverage Orkut OpenSocial API from within the familiar Visual Studio environment. PasteHtml.NET: PasteHtml.NET is a .NET API for using the PasteHtml.com service.Photon: Silverlight MVVM Framework RSATasync: Running analyses in RiskSpectrum PSA Professional software is a time-consuming task. RSATasync is a middleware, which uses .NET4 Parallel Extensions to parallelize analyses sent by the editor to the analyzer in the RiskSpectrum software.The Killie01 Project: all killie01 projects (opensource)United Nations News for Windows Phone 7: Open source project for United Nations News for Windows Phone 7. WCF SIP Stack: WCF SIPWordpress .NET: WPDotnet is a library to ease the Wordpress integration with ASP.NET. Some Server controls are implemented. If you don't want to use them, you can just use the classes.

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• NullReferenceException when accessing variables in a 2D array in Unity

  - by Syed

  I have made a class including variables in Monodevelop which is: public class GridInfo : MonoBehaviour { public float initPosX; public float initPosY; public bool inUse; public int f; public int g; public int h; public GridInfo parent; public int y,x; } Now I am using its class variable in another class, Map.cs which is: public class Map : MonoBehaviour { public static GridInfo[,] Tile = new GridInfo[17, 23]; void Start() { Tile[0,0].initPosX = initPosX; //Line 49 } } I am not getting any error on runtime, but when I play in unity it is giving me error NullReferenceException: Object reference not set to an instance of an object Map.Start () (at Assets/Scripts/Map.cs:49) I am not inserting this script in any gameobject, as Map.cs will make a GridInfo type array, I have also tried using variables using GetComponent, where is the problem ?

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• SQL SERVER – 2011 – Introduction to SEQUENCE – Simple Example of SEQUENCE

  - by pinaldave

  SQL Server 2011 will contain one of the very interesting feature called SEQUENCE. I have waited for this feature for really long time. I am glad it is here finally. SEQUENCE allows you to define a single point of repository where SQL Server will maintain in memory counter. USE AdventureWorks2008R2 GO CREATE SEQUENCE [Seq] AS [int] START WITH 1 INCREMENT BY 1 MAXVALUE 20000 GO SEQUENCE is very interesting concept and I will write few blog post on this subject in future. Today we will see only working example of the same. Let us create a sequence. We can specify various values like start value, increment value as well maxvalue. -- First Run SELECT NEXT VALUE FOR Seq, c.CustomerID FROM Sales.Customer c GO -- Second Run SELECT NEXT VALUE FOR Seq, c.AccountNumber FROM Sales.Customer c GO Once the sequence is defined, it can be fetched using following method. Every single time new incremental value is provided, irrespective of sessions. Sequence will generate values till the max value specified. Once the max value is reached, query will stop and will return error message. Msg 11728, Level 16, State 1, Line 2 The sequence object ‘Seq’ has reached its minimum or maximum value. Restart the sequence object to allow new values to be generated. We can restart the sequence from any particular value and it will work fine. -- Restart the Sequence ALTER SEQUENCE [Seq] RESTART WITH 1 GO -- Sequence Restarted SELECT NEXT VALUE FOR Seq, c.CustomerID FROM Sales.Customer c GO Let us do final clean up. -- Clean Up DROP SEQUENCE [Seq] GO There are lots of things one can find useful about this feature. We will see that in future posts. Here is the complete code for easy reference. USE AdventureWorks2008R2 GO CREATE SEQUENCE [Seq] AS [int] START WITH 1 INCREMENT BY 1 MAXVALUE 20000 GO -- First Run SELECT NEXT VALUE FOR Seq, c.CustomerID FROM Sales.Customer c GO -- Second Run SELECT NEXT VALUE FOR Seq, c.AccountNumber FROM Sales.Customer c GO -- Restart the Sequence ALTER SEQUENCE [Seq] RESTART WITH 1 GO -- Sequence Restarted SELECT NEXT VALUE FOR Seq, c.CustomerID FROM Sales.Customer c GO -- Clean Up DROP SEQUENCE [Seq] GO 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, SQLServer, T SQL, Technology

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• Objective C style nil in java?

  - by Usman Ismail

  Objective C has a concept of a nil object which would accept any method call with any parameters without complaining and silently return another nil. I have used something similar in Java using easymock and mockito for testing. Is there something similar for main line code? Is it even a good idea to have something like this? One use-case where I am considering using it is with optional metrics. We have codahale metrics counters on which we call mark() every time an event is generated. This is surrounded by an If/then to check for metrics enabled flag. I could just use a nil object as counter and silently accept the mark call if metrics are not enabled.

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• Convert Dynamic to Type and convert Type to Dynamic

  - by Jon Canning

  public static class DynamicExtensions     {         public static T FromDynamic<T>(this IDictionary<string, object> dictionary)         {             var bindings = new List<MemberBinding>();             foreach (var sourceProperty in typeof(T).GetProperties().Where(x => x.CanWrite))             {                 var key = dictionary.Keys.SingleOrDefault(x => x.Equals(sourceProperty.Name, StringComparison.OrdinalIgnoreCase));                 if (string.IsNullOrEmpty(key)) continue;                 var propertyValue = dictionary[key];                 bindings.Add(Expression.Bind(sourceProperty, Expression.Constant(propertyValue)));             }             Expression memberInit = Expression.MemberInit(Expression.New(typeof(T)), bindings);             return Expression.Lambda<Func<T>>(memberInit).Compile().Invoke();         }         public static dynamic ToDynamic<T>(this T obj)         {             IDictionary<string, object> expando = new ExpandoObject();             foreach (var propertyInfo in typeof(T).GetProperties())             {                 var propertyExpression = Expression.Property(Expression.Constant(obj), propertyInfo);                 var currentValue = Expression.Lambda<Func<string>>(propertyExpression).Compile().Invoke();                 expando.Add(propertyInfo.Name.ToLower(), currentValue);             }             return expando as ExpandoObject;         }     }

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• Error trapping for a missing data source in a Spring MVC / Spring JDBC web app [migrated]

  - by Geeb

  I have written a web app that uses Spring MVC libraries and Spring JDBC to connect to an Oracle DB. (I don't use any ORM type libraries as I create stored procedures on Oracle that do my stuff and I'm quite happy with that.) I use a connection pool to Oracle managed by the Tomcat container The app generally works absolutely fine by the way! BUT... I noticed the other day when I tried to set up the app on another Tomcat instance that I had forgotten to configure the connection pool and obviously the app could not get hold of an org.apache.commons.dbcp.BasicDataSource object, so it crashed. I define the pool params in the tomcat "context.conf" In my "web.xml" I have: <servlet> <servlet-name>appServlet</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <init-param> <param-name>contextConfigLocation</param-name> <param-value>/WEB-INF/Spring/appServlet/servlet-context.xml</param-value> </init-param> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>appServlet</servlet-name> <!-- Map *everything* to appServlet --> <url-pattern>/</url-pattern> </servlet-mapping> <resource-ref> <description>Oracle Datasource example</description> <res-ref-name>jdbc/ora1</res-ref-name> <res-type>org.apache.commons.dbcp.BasicDataSource</res-type> <res-auth>Container</res-auth> </resource-ref> And I have a Spring "servlet-context.xml" where JNDI is used to map the data source object provided by the connection pool to a Spring bean with the ID of "dataSource": <jee:jndi-lookup id="dataSource" jndi-name="java:comp/env/jdbc/ora1" resource-ref="true" /> Here's the question: Where do I trap the case where the database cannot be accessed for whatever reason? I don't want the user to see a yard-and-a-half of Java stack trace in their browser, rather a nicer message that tells them there is a database problem etc. It seems that my app tries to configure the "dataSource" bean (in "servlet-context.xml") before any code has tested it can actually provide a dataSource object from the pool?! Maybe I'm not fully understanding exactly what is going on in these stages of the app firing up ... Thanks for any advice!

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• Deleting multiple objects in a AWS S3 bucket with s3curl.pl?

  - by user183394

  I have been trying to use the AWS "official" command line tool s3curl.pl to test out the recently announced multi-object delete. Here is what I have done: First, I tested out the s3curl.pl with a set of credentials without a hitch: $ s3curl.pl --id=s3 -- http://testbucket-0.s3.amazonaws.com/|xmllint --format - % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 100 884 0 884 0 0 4399 0 --:--:-- --:--:-- --:--:-- 5703 <?xml version="1.0" encoding="UTF-8"?> <ListBucketResult xmlns="http://s3.amazonaws.com/doc/2006-03-01/"> <Name>testbucket-0</Name> <Prefix/> <Marker/> <MaxKeys>1000</MaxKeys> <IsTruncated>false</IsTruncated> <Contents> <Key>file_1</Key> <LastModified>2012-03-22T17:08:17.000Z</LastModified> <ETag>"ee0e521a76524034aaa5b331842a8b4e"</ETag> <Size>400000</Size> <Owner> <ID>e6d81ea69572270e58d3814ab674df8c8f1fd5d502669633a4951bdd5185f7f4</ID> <DisplayName>zackp</DisplayName> </Owner> <StorageClass>STANDARD</StorageClass> </Contents> <Contents> <Key>file_2</Key> <LastModified>2012-03-22T17:08:19.000Z</LastModified> <ETag>"6b32cbf8219a59690a9f69ba6ff3f590"</ETag> <Size>600000</Size> <Owner> <ID>e6d81ea69572270e58d3814ab674df8c8f1fd5d502669633a4951bdd5185f7f4</ID> <DisplayName>zackp</DisplayName> </Owner> <StorageClass>STANDARD</StorageClass> </Contents> </ListBucketResult> Then, I following the s3curl.pl's usage instructions: s3curl.pl --help Usage /usr/local/bin/s3curl.pl --id friendly-name (or AWSAccessKeyId) [options] -- [curl-options] [URL] options: --key SecretAccessKey id/key are AWSAcessKeyId and Secret (unsafe) --contentType text/plain set content-type header --acl public-read use a 'canned' ACL (x-amz-acl header) --contentMd5 content_md5 add x-amz-content-md5 header --put <filename> PUT request (from the provided local file) --post [<filename>] POST request (optional local file) --copySrc bucket/key Copy from this source key --createBucket [<region>] create-bucket with optional location constraint --head HEAD request --debug enable debug logging common curl options: -H 'x-amz-acl: public-read' another way of using canned ACLs -v verbose logging Then, I tried the following, and always got back error. I would appreciated it very much if someone could point out where I made a mistake? $ s3curl.pl --id=s3 --post multi_delete.xml -- http://testbucket-0.s3.amazonaws.com/?delete <?xml version="1.0" encoding="UTF-8"?> <Error><Code>SignatureDoesNotMatch</Code><Message>The request signature we calculated does not match the signature you provided. Check your key and signing method.</Message><StringToSignBytes>50 4f 53 54 0a 0a 0a 54 68 75 2c 20 30 35 20 41 70 72 20 32 30 31 32 20 30 30 3a 35 30 3a 30 38 20 2b 30 30 30 30 0a 2f 7a 65 74 74 61 72 2d 74 2f 3f 64 65 6c 65 74 65</StringToSignBytes><RequestId>707FBE0EB4A571A8</RequestId><HostId>mP3ZwlPTcRqARQZd6gU4UvBrxGBNIVa0VVe5p0rqGmq5hM65RprwcG/qcXe+pmDT</HostId><SignatureProvided>edkNGuugiSFe0ku4eGzkh8kYgHw=</SignatureProvided><StringToSign>POST Thu, 05 Apr 2012 00:50:08 +0000 The file multi_delete.xml contains the following: cat multi_delete.xml <?xml version="1.0" encoding="UTF-8"?> <Delete> <Quiet>true</Quiet> <Object> <Key>file_1</Key> <VersionId> </VersionId>> </Object> <Object> <Key>file_2</Key> <VersionId> </VersionId> </Object> </Delete> Thanks for any help! --Zack

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• ASP.NET Web API and Simple Value Parameters from POSTed data

  - by Rick Strahl

  In testing out various features of Web API I've found a few oddities in the way that the serialization is handled. These are probably not super common but they may throw you for a loop. Here's what I found. Simple Parameters from Xml or JSON Content Web API makes it very easy to create action methods that accept parameters that are automatically parsed from XML or JSON request bodies. For example, you can send a JavaScript JSON object to the server and Web API happily deserializes it for you. This works just fine:public string ReturnAlbumInfo(Album album) { return album.AlbumName + " (" + album.YearReleased.ToString() + ")"; } However, if you have methods that accept simple parameter types like strings, dates, number etc., those methods don't receive their parameters from XML or JSON body by default and you may end up with failures. Take the following two very simple methods:public string ReturnString(string message) { return message; } public HttpResponseMessage ReturnDateTime(DateTime time) { return Request.CreateResponse<DateTime>(HttpStatusCode.OK, time); } The first one accepts a string and if called with a JSON string from the client like this:var client = new HttpClient(); var result = client.PostAsJsonAsync<string>(http://rasxps/AspNetWebApi/albums/rpc/ReturnString, "Hello World").Result; which results in a trace like this: POST http://rasxps/AspNetWebApi/albums/rpc/ReturnString HTTP/1.1Content-Type: application/json; charset=utf-8Host: rasxpsContent-Length: 13Expect: 100-continueConnection: Keep-Alive "Hello World" produces… wait for it: null. Sending a date in the same fashion:var client = new HttpClient(); var result = client.PostAsJsonAsync<DateTime>(http://rasxps/AspNetWebApi/albums/rpc/ReturnDateTime, new DateTime(2012, 1, 1)).Result; results in this trace: POST http://rasxps/AspNetWebApi/albums/rpc/ReturnDateTime HTTP/1.1Content-Type: application/json; charset=utf-8Host: rasxpsContent-Length: 30Expect: 100-continueConnection: Keep-Alive "\/Date(1325412000000-1000)\/" (yes still the ugly MS AJAX date, yuk! This will supposedly change by RTM with Json.net used for client serialization) produces an error response: The parameters dictionary contains a null entry for parameter 'time' of non-nullable type 'System.DateTime' for method 'System.Net.Http.HttpResponseMessage ReturnDateTime(System.DateTime)' in 'AspNetWebApi.Controllers.AlbumApiController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter. Basically any simple parameters are not parsed properly resulting in null being sent to the method. For the string the call doesn't fail, but for the non-nullable date it produces an error because the method can't handle a null value. This behavior is a bit unexpected to say the least, but there's a simple solution to make this work using an explicit [FromBody] attribute:public string ReturnString([FromBody] string message) andpublic HttpResponseMessage ReturnDateTime([FromBody] DateTime time) which explicitly instructs Web API to read the value from the body. UrlEncoded Form Variable Parsing Another similar issue I ran into is with POST Form Variable binding. Web API can retrieve parameters from the QueryString and Route Values but it doesn't explicitly map parameters from POST values either. Taking our same ReturnString function from earlier and posting a message POST variable like this:var formVars = new Dictionary<string,string>(); formVars.Add("message", "Some Value"); var content = new FormUrlEncodedContent(formVars); var client = new HttpClient(); var result = client.PostAsync(http://rasxps/AspNetWebApi/albums/rpc/ReturnString, content).Result; which produces this trace: POST http://rasxps/AspNetWebApi/albums/rpc/ReturnString HTTP/1.1Content-Type: application/x-www-form-urlencodedHost: rasxpsContent-Length: 18Expect: 100-continue message=Some+Value When calling ReturnString:public string ReturnString(string message) { return message; } unfortunately it does not map the message value to the message parameter. This sort of mapping unfortunately is not available in Web API. Web API does support binding to form variables but only as part of model binding, which binds object properties to the POST variables. Sending the same message as in the previous example you can use the following code to pick up POST variable data:public string ReturnMessageModel(MessageModel model) { return model.Message; } public class MessageModel { public string Message { get; set; }} Note that the model is bound and the message form variable is mapped to the Message property as would other variables to properties if there were more. This works but it's not very dynamic. There's no real easy way to retrieve form variables (or query string values for that matter) in Web API's Request object as far as I can discern. Well only if you consider this easy:public string ReturnString() { var formData = Request.Content.ReadAsAsync<FormDataCollection>().Result; return formData.Get("message"); } Oddly FormDataCollection does not allow for indexers to work so you have to use the .Get() method which is rather odd. If you're running under IIS/Cassini you can always resort to the old and trusty HttpContext access for request data:public string ReturnString() { return HttpContext.Current.Request.Form["message"]; } which works fine and is easier. It's kind of a bummer that HttpRequestMessage doesn't expose some sort of raw Request object that has access to dynamic data - given that it's meant to serve as a generic REST/HTTP API that seems like a crucial missing piece. I don't see any way to read query string values either. To me personally HttpContext works, since I don't see myself using self-hosted code much.© Rick Strahl, West Wind Technologies, 2005-2012Posted in Web Api   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• links for 2010-04-06

  - by Bob Rhubart

  Dean Halbeisen: Best Practices for Network Backup (Sun StorageTek) Dean Halbeisen's white paper describes the Oracle reference architecture for next-generation data backup using Sun StorageTek Enterprise Backup software. (tags: entarch oracle otn sun enterprisearchitecture storagetek)

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• How to prevent ‘Select *’ : The elegant way

  - by Dave Ballantyne

  I’ve been doing a lot of work with the “Microsoft SQL Server 2012 Transact-SQL Language Service” recently, see my post here and article here for more details on its use and some uses. An obvious use is to interrogate sql scripts to enforce our coding standards.  In the SQL world a no-brainer is SELECT *,  all apologies must now be given to Jorge Segarra and his post “How To Prevent SELECT * The Evil Way” as this is a blatant rip-off IMO, the only true way to check for this particular evilness is to parse the SQL as if we were SQL Server itself.  The parser mentioned above is ,pretty much, the best tool for doing this.  So without further ado lets have a look at a powershell script that does exactly that : cls #Load the assembly [System.Reflection.Assembly]::LoadWithPartialName("Microsoft.SqlServer.Management.SqlParser") | Out-Null $ParseOptions = New-Object Microsoft.SqlServer.Management.SqlParser.Parser.ParseOptions $ParseOptions.BatchSeparator = 'GO' #Create the object $Parser = new-object Microsoft.SqlServer.Management.SqlParser.Parser.Scanner($ParseOptions) $SqlArr = Get-Content "C:\scripts\myscript.sql" $Sql = "" foreach($Line in $SqlArr){ $Sql+=$Line $Sql+="`r`n" } $Parser.SetSource($Sql,0) $Token=[Microsoft.SqlServer.Management.SqlParser.Parser.Tokens]::TOKEN_SET $IsEndOfBatch = $false $IsMatched = $false $IsExecAutoParamHelp = $false $Batch = "" $BatchStart =0 $Start=0 $End=0 $State=0 $SelectColumns=@(); $InSelect = $false $InWith = $false; while(($Token = $Parser.GetNext([ref]$State ,[ref]$Start, [ref]$End, [ref]$IsMatched, [ref]$IsExecAutoParamHelp ))-ne [Microsoft.SqlServer.Management.SqlParser.Parser.Tokens]::EOF) { $Str = $Sql.Substring($Start,($End-$Start)+1) try{ ($TokenPrs =[Microsoft.SqlServer.Management.SqlParser.Parser.Tokens]$Token) | Out-Null #Write-Host $TokenPrs if($TokenPrs -eq [Microsoft.SqlServer.Management.SqlParser.Parser.Tokens]::TOKEN_SELECT){ $InSelect =$true $SelectColumns+="" } if($TokenPrs -eq [Microsoft.SqlServer.Management.SqlParser.Parser.Tokens]::TOKEN_FROM){ $InSelect =$false #Write-Host $SelectColumns -BackgroundColor Red foreach($Col in $SelectColumns){ if($Col.EndsWith("*")){ Write-Host "select * is not allowed" exit } } $SelectColumns =@() } }catch{ #$Error $TokenPrs = $null } if($InSelect -and $TokenPrs -ne [Microsoft.SqlServer.Management.SqlParser.Parser.Tokens]::TOKEN_SELECT){ if($Str -eq ","){ $SelectColumns+="" }else{ $SelectColumns[$SelectColumns.Length-1]+=$Str } } } OK, im not going to pretend that its the prettiest of powershell scripts,  but if our parsed script file “C:\Scripts\MyScript.SQL” contains SELECT * then “select * is not allowed” will be written to the host.  So, where can this go wrong ?  It cant ,or at least shouldn’t , go wrong, but it is lacking in functionality.  IMO, Select * should be allowed in CTEs, views and Inline table valued functions at least and as it stands they will be reported upon. Anyway, it is a start and is more reliable that other methods.

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• GNU Smalltalk package

  - by Peter

  I've installed the GNU Smalltalk package and can get to the SmallTalk command line with the command 'gst'. However, I can't start the visual gst browser using the command: $ gst-browser When I try, this is what I get: peter@peredur:~$ gst-browser Object: CFunctionDescriptor new: 1 "<0x40488720>" error: Invalid C call-out gdk_colormap_get_type SystemExceptions.CInterfaceError(Smalltalk.Exception)>>signal (ExcHandling.st:254) SystemExceptions.CInterfaceError class(Smalltalk.Exception class)>>signal: (ExcHandling.st:161) Smalltalk.CFunctionDescriptor(Smalltalk.CCallable)>>callInto: (CCallable.st:165) GdkColormap class>>getType (GTK.star#VFS.ZipFile/Funcs.st:1) optimized [] in GLib class>>registerAllTypes (GTK.star#VFS.ZipFile/GtkDecl.st:78) Smalltalk.OrderedCollection>>do: (OrderColl.st:68) GLib class>>registerAllTypes (GTK.star#VFS.ZipFile/GtkDecl.st:78) Smalltalk.UndefinedObject>>executeStatements (GTK.star#VFS.ZipFile/GtkImpl.st:1078) Object: CFunctionDescriptor new: 1 "<0x404a7c28>" error: Invalid C call-out gtk_window_new SystemExceptions.CInterfaceError(Exception)>>signal (ExcHandling.st:254) SystemExceptions.CInterfaceError class(Exception class)>>signal: (ExcHandling.st:161) CFunctionDescriptor(CCallable)>>callInto: (CCallable.st:165) GTK.GtkWindow class>>new: (GTK.star#VFS.ZipFile/Funcs.st:1) VisualGST.GtkDebugger(VisualGST.GtkMainWindow)>>initialize (VisualGST.star#VFS.ZipFile/GtkMainWindow.st:131) VisualGST.GtkDebugger class(VisualGST.GtkMainWindow class)>>openSized: (VisualGST.star#VFS.ZipFile/GtkMainWindow.st:19) [] in VisualGST.GtkDebugger class>>open: (VisualGST.star#VFS.ZipFile/Debugger/GtkDebugger.st:16) [] in BlockClosure>>forkDebugger (DebugTools.star#VFS.ZipFile/DebugTools.st:380) [] in Process>>onBlock:at:suspend: (Process.st:392) BlockClosure>>on:do: (BlkClosure.st:193) [] in Process>>onBlock:at:suspend: (Process.st:393) BlockClosure>>ensure: (BlkClosure.st:269) [] in Process>>onBlock:at:suspend: (Process.st:370) [] in BlockClosure>>asContext: (BlkClosure.st:179) BlockContext class>>fromClosure:parent: (BlkContext.st:68) Everything hangs at this point until I hit ^C, after which, I get: Object: CFunctionDescriptor new: 1 "<0x404a7c28>" error: Invalid C call-out gtk_window_new SystemExceptions.CInterfaceError(Exception)>>signal (ExcHandling.st:254) SystemExceptions.CInterfaceError class(Exception class)>>signal: (ExcHandling.st:161) CFunctionDescriptor(CCallable)>>callInto: (CCallable.st:165) GTK.GtkWindow class>>new: (GTK.star#VFS.ZipFile/Funcs.st:1) VisualGST.GtkDebugger(VisualGST.GtkMainWindow)>>initialize (VisualGST.star#VFS.ZipFile/GtkMainWindow.st:131) VisualGST.GtkDebugger class(VisualGST.GtkMainWindow class)>>openSized: (VisualGST.star#VFS.ZipFile/GtkMainWindow.st:19) [] in VisualGST.GtkDebugger class>>open: (VisualGST.star#VFS.ZipFile/Debugger/GtkDebugger.st:16) [] in BlockClosure>>forkDebugger (DebugTools.star#VFS.ZipFile/DebugTools.st:380) [] in Process>>onBlock:at:suspend: (Process.st:392) BlockClosure>>on:do: (BlkClosure.st:193) [] in Process>>onBlock:at:suspend: (Process.st:393) BlockClosure>>ensure: (BlkClosure.st:269) [] in Process>>onBlock:at:suspend: (Process.st:370) [] in BlockClosure>>asContext: (BlkClosure.st:179) BlockContext class>>fromClosure:parent: (BlkContext.st:68) peter@peredur:~$ Is there a problem with this package?

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• Chunking a List - .NET vs Python

  - by Abhijeet Patel

  Chunking a List As I mentioned last time, I'm knee deep in python these days. I come from a statically typed background so it's definitely a mental adjustment. List comprehensions is BIG in Python and having worked with a few of them I can see why. Let's say we need to chunk a list into sublists of a specified size. Here is how we'd do it in C#  static class Extensions   {       public static IEnumerable<List<T>> Chunk<T>(this List<T> l, int chunkSize)       {           if (chunkSize <0)           {               throw new ArgumentException("chunkSize cannot be negative", "chunkSize");           }           for (int i = 0; i < l.Count; i += chunkSize)           {               yield return new List<T>(l.Skip(i).Take(chunkSize));           }       }    }    static void Main(string[] args)  {           var l = new List<string> { "a", "b", "c", "d", "e", "f","g" };             foreach (var list in l.Chunk(7))           {               string str = list.Aggregate((s1, s2) => s1 + "," + s2);               Console.WriteLine(str);           }   }   A little wordy but still pretty concise thanks to LINQ.We skip the iteration number plus chunkSize elements and yield out a new List of chunkSize elements on each iteration. The python implementation is a bit more terse. def chunkIterable(iter, chunkSize):      '''Chunks an iterable         object into a list of the specified chunkSize     '''        assert hasattr(iter, "__iter__"), "iter is not an iterable"      for i in xrange(0, len(iter), chunkSize):          yield iter[i:i + chunkSize]    if __name__ == '__main__':      l = ['a', 'b', 'c', 'd', 'e', 'f']      generator = chunkIterable(l,2)      try:          while(1):              print generator.next()      except StopIteration:          pass   xrange generates elements in the specified range taking in a seed and returning a generator. which can be used in a for loop(much like using a C# iterator in a foreach loop) Since chunkIterable has a yield statement, it turns this method into a generator as well. iter[i:i + chunkSize] essentially slices the list based on the current iteration index and chunksize and creates a new list that we yield out to the caller one at a time. A generator much like an iterator is a state machine and each subsequent call to it remembers the state at which the last call left off and resumes execution from that point. The caveat to keep in mind is that since variables are not explicitly typed we need to ensure that the object passed in is iterable using hasattr(iter, "__iter__").This way we can perform chunking on any object which is an "iterable", very similar to accepting an IEnumerable in the .NET land

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• How to wire finite state machine into component-based architecture?

  - by Pup

  State machines seem to cause harmful dependencies in component-based architectures. How, specifically, is communication handled between a state machine and the components that carry out state-related behavior? Where I'm at: I'm new to component-based architectures. I'm making a fighting game, although I don't think that should matter. I envision my state machine being used to toggle states like "crouching", "dashing", "blocking", etc. I've found this state-management technique to be the most natural system for a component-based architecture, but it conflicts with techniques I've read about: Dynamic Game Object Component System for Mutable Behavior Characters It suggests that all components activate/deactivate themselves by continually checking a condition for activation. I think that actions like "running" or "walking" make sense as states, which is in disagreement with the accepted response here: finite state machine used in mario like platform game I've found this useful, but ambiguous: How to implement behavior in a component-based game architecture? It suggests having a separate component that contains nothing but a state machine. But, this necessitates some kind of coupling between the state machine component and nearly all the other components. I don't understand how this coupling should be handled. These are some guesses: A. Components depend on state machine: Components receive reference to state machine component's getState(), which returns an enumeration constant. Components update themselves regularly and check this as needed. B. State machine depends on components: The state machine component receives references to all the components it's monitoring. It queries their getState() methods to see where they're at. C. Some abstraction between them Use an event hub? Command pattern? D. Separate state objects that reference components State Pattern is used. Separate state objects are created, which activate/deactivate a set of components. State machine switches between state objects. I'm looking at components as implementations of aspects. They do everything that's needed internally to make that aspect happen. It seems like components should function on their own, without relying on other components. I know some dependencies are necessary, but state machines seem to want to control all of my components.

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• SQL SERVER – Replace a Column Name in Multiple Stored Procedure all together

  - by pinaldave

  I receive a lot of emails every day. I try to answer each and every email and comments on Facebook and Twitter. I prefer communication on social media as this gives opportunities to others to read the questions and participate along with me. There is always some question which everyone likes to read and remember. Here is one of the questions which I received in email. I believe the same question will be there any many developers who are beginning with SQL Server. I decided to blog about it so everyone can read it and participate. “I am beginner in SQL Server. I have a very interesting situation and need your help. I am beginner to SQL Server and that is why I do not have access to the production server and I work entirely on the development server. The project I am working on is also in the infant stage as well. In product I had to create a multiple tables and every table had few columns. Later on I have written Stored Procedures using those tables. During a code review my manager has requested to change one of the column which I have used in the table. As per him the naming convention was not accurate. Now changing the columname in the table is not a big issue. I figured out that I can do it very quickly either using T-SQL script or SQL Server Management Studio. The real problem is that I have used this column in nearly 50+ stored procedure. This looks like a very mechanical task. I believe I can go and change it in nearly 50+ stored procedure but is there a better solution I can use. Someone suggested that I should just go ahead and find the text in system table and update it there. Is that safe solution? If not, what is your solution. In simple words, How to replace a column name in multiple stored procedure efficiently and quickly? Please help me here with keeping my experience and non-production server in mind.” Well, I found this question very interesting. Honestly I would have preferred if this question was asked on my social media handles (Facebook and Twitter) as I am very active there and quite often before I reach there other experts have already answered this question. Anyway I am now answering the same question on the blog so all of us can participate here and come up with an appropriate answer. Here is my answer - “My Friend, I do not advice to touch system table. Please do not go that route. It can be dangerous and not appropriate. The issue which you faced today is what I used to face in early career as well I still face it often. There are two sets of argument I have observed – there are people who see no value in the name of the object and name objects like obj1, obj2 etc. There are sets of people who carefully chose the name of the object where object name is self-explanatory and almost tells a story. I am not here to take any side in this blog post – so let me go to a quick solution for your problem. Note: Following should not be directly practiced on Production Server. It should be properly tested on development server and once it is validated they should be pushed to your production server with your existing deployment practice. The answer is here assuming you have regular stored procedures and you are working on the Development NON Production Server. Go to Server Note >> Databases >> DatabaseName >> Programmability >> Stored Procedure Now make sure that Object Explorer Details are open (if not open it by clicking F7). You will see the list of all the stored procedures there. Now you will see a list of all the stored procedures on the right side list. Select either all of them or the one which you believe are relevant to your query. Now… Right click on the stored procedures >> SELECT DROP and CREATE to >> Now select New Query Editor Window or Clipboard. Paste the complete script to a new window if you have selected Clipboard option. Now press Control+H which will bring up the Find and Replace Screen. In this screen insert the column to be replaced in the “Find What”box and new column name into “Replace With” box. Now execute the whole script. As we have selected DROP and CREATE to, it will created drop the old procedure and create the new one. Another method would do all the same procedure but instead of DROP and CREATE manually replace the CREATE word with ALTER world. There is a small advantage in doing this is that if due to any reason the error comes up which prevents the new stored procedure to be created you will have your old stored procedure in the system as it is. “ Well, this was my answer to the question which I have received. Do you see any other workaround or solution? Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Server Management Studio, SQL Stored Procedure, SQL Tips and Tricks, T SQL, Technology

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• How to implement Undo and Redo feature in as3

  - by Swati Singh

  I am going to create an application in that i have to implement an Undo and Redo feature. In the application there will be multiple objects located on stage and user can customize the position of the objects. But when user clicks on Undo the object go back to their default position and after clicking on redo object will move on the new position. So my question is how can i apply these feature in my application? Is there any library or any third party classes? Can some one help me? Thanks in advance.

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• SQL SERVER – Identify Numbers of Non Clustered Index on Tables for Entire Database

  - by pinaldave

  Here is the script which will give you numbers of non clustered indexes on any table in entire database. SELECT COUNT(i.TYPE) NoOfIndex, [schema_name] = s.name, table_name = o.name FROM sys.indexes i INNER JOIN sys.objects o ON i.[object_id] = o.[object_id] INNER JOIN sys.schemas s ON o.[schema_id] = s.[schema_id] WHERE o.TYPE IN ('U') AND i.TYPE = 2 GROUP BY s.name, o.name ORDER BY schema_name, table_name Here is the small story behind why this script was needed. I recently went to meet my friend in his office and he introduced me to his colleague in office as someone who is an expert in SQL Server Indexing. I politely said I am yet learning about Indexing and have a long way to go. My friend’s colleague right away said – he had a suggestion for me with related to Index. According to him he was looking for a script which will count all the non clustered on all the tables in the database and he was not able to find that on SQLAuthority.com. I was a bit surprised as I really do not remember all the details about what I have written so far. I quickly pull up my phone and tried to look for the script on my custom search engine and he was correct. I never wrote a script which will count all the non clustered indexes on tables in the whole database. Excessive indexing is not recommended in general. If you have too many indexes it will definitely negatively affect your performance. The above query will quickly give you details of numbers of indexes on tables on your entire database. You can quickly glance and use the numbers as reference. Please note that the number of the index is not a indication of bad indexes. There is a lot of wisdom I can write here but that is not the scope of this blog post. There are many different rules with Indexes and many different scenarios. For example – a table which is heap (no clustered index) is often not recommended on OLTP workload (here is the blog post to identify them), drop unused indexes with careful observation (here is the script for it), identify missing indexes and after careful testing add them (here is the script for it). Even though I have given few links here it is just the tip of the iceberg. If you follow only above four advices your ship may still sink. Those who wants to learn the subject in depth can watch the videos here after logging in. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Index, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• Pure Front end JavaScript with Web API versus MVC views with ajax

  - by eyeballpaul

  This was more a discussion for what peoples thoughts are these days on how to split a web application. I am used to creating an MVC application with all its views and controllers. I would normally create a full view and pass this back to the browser on a full page request, unless there were specific areas that I did not want to populate straight away and would then use DOM page load events to call the server to load other areas using AJAX. Also, when it came to partial page refreshing, I would call an MVC action method which would return the HTML fragment which I could then use to populate parts of the page. This would be for areas that I did not want to slow down initial page load, or areas that fitted better with AJAX calls. One example would be for table paging. If you want to move on to the next page, I would prefer it if an AJAX call got that info rather than using a full page refresh. But the AJAX call would still return an HTML fragment. My question is. Are my thoughts on this archaic because I come from a .net background rather than a pure front end background? An intelligent front end developer that I work with, prefers to do more or less nothing in the MVC views, and would rather do everything on the front end. Right down to web API calls populating the page. So that rather than calling an MVC action method, which returns HTML, he would prefer to return a standard object and use javascript to create all the elements of the page. The front end developer way means that any benefits that I normally get with MVC model validation, including client side validation, would be gone. It also means that any benefits that I get with creating the views, with strongly typed html templates etc would be gone. I believe this would mean I would need to write the same validation for front end and back end validation. The javascript would also need to have lots of methods for creating all the different parts of the DOM. For example, when adding a new row to a table, I would normally use the MVC partial view for creating the row, and then return this as part of the AJAX call, which then gets injected into the table. By using a pure front end way, the javascript would would take in an object (for, say, a product) for the row from the api call, and then create a row from that object. Creating each individual part of the table row. The website in question will have lots of different areas, from administration, forms, product searching etc. A website that I don't think requires to be architected in a single page application way. What are everyone's thoughts on this? I am interested to hear from front end devs and back end devs.

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• Mise à jour du cours vidéo Python pour débutants par Pythonnerie, trois nouvelles vidéos sur les interfaces graphiques

  voici un tutoriel, destiné à des débutants en informatique, utilise la vidéo pour aider à visualiser les concepts. Cours vidéo Python pour débutants Ce tutoriel est un travail en cours, qui sera (doucement) enrichi et complété au fil du temps. Bien entendu, il n'a aucune prétention à remplacer la documentation de référence, qu'il espère simplement rendre indirectement plus accessible. Mais son auteur espère avoir confirmé le goût de l'informatique chez ceux qui l'avaient déjà et montré aux autres que la programmation n'est pas forcément rébarbative ni mystérieuse....

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• How I understood monads, part 1/2: sleepless and self-loathing in Seattle

  - by Bertrand Le Roy

  For some time now, I had been noticing some interest for monads, mostly in the form of unintelligible (to me) blog posts and comments saying “oh, yeah, that’s a monad” about random stuff as if it were absolutely obvious and if I didn’t know what they were talking about, I was probably an uneducated idiot, ignorant about the simplest and most fundamental concepts of functional programming. Fair enough, I am pretty much exactly that. Being the kind of guy who can spend eight years in college just to understand a few interesting concepts about the universe, I had to check it out and try to understand monads so that I too can say “oh, yeah, that’s a monad”. Man, was I hit hard in the face with the limitations of my own abstract thinking abilities. All the articles I could find about the subject seemed to be vaguely understandable at first but very quickly overloaded the very few concept slots I have available in my brain. They also seemed to be consistently using arcane notation that I was entirely unfamiliar with. It finally all clicked together one Friday afternoon during the team’s beer symposium when Louis was patient enough to break it down for me in a language I could understand (C#). I don’t know if being intoxicated helped. Feel free to read this with or without a drink in hand. So here it is in a nutshell: a monad allows you to manipulate stuff in interesting ways. Oh, OK, you might say. Yeah. Exactly. Let’s start with a trivial case: public static class Trivial { public static TResult Execute<T, TResult>( this T argument, Func<T, TResult> operation) { return operation(argument); } } This is not a monad. I removed most concepts here to start with something very simple. There is only one concept here: the idea of executing an operation on an object. This is of course trivial and it would actually be simpler to just apply that operation directly on the object. But please bear with me, this is our first baby step. Here’s how you use that thing: "some string" .Execute(s => s + " processed by trivial proto-monad.") .Execute(s => s + " And it's chainable!"); What we’re doing here is analogous to having an assembly chain in a factory: you can feed it raw material (the string here) and a number of machines that each implement a step in the manufacturing process and you can start building stuff. The Trivial class here represents the empty assembly chain, the conveyor belt if you will, but it doesn’t care what kind of raw material gets in, what gets out or what each machine is doing. It is pure process. A real monad will need a couple of additional concepts. Let’s say the conveyor belt needs the material to be processed to be contained in standardized boxes, just so that it can safely and efficiently be transported from machine to machine or so that tracking information can be attached to it. Each machine knows how to treat raw material or partly processed material, but it doesn’t know how to treat the boxes so the conveyor belt will have to extract the material from the box before feeding it into each machine, and it will have to box it back afterwards. This conveyor belt with boxes is essentially what a monad is. It has one method to box stuff, one to extract stuff from its box and one to feed stuff into a machine. So let’s reformulate the previous example but this time with the boxes, which will do nothing for the moment except containing stuff. public class Identity<T> { public Identity(T value) { Value = value; } public T Value { get; private set;} public static Identity<T> Unit(T value) { return new Identity<T>(value); } public static Identity<U> Bind<U>( Identity<T> argument, Func<T, Identity<U>> operation) { return operation(argument.Value); } } Now this is a true to the definition Monad, including the weird naming of the methods. It is the simplest monad, called the identity monad and of course it does nothing useful. Here’s how you use it: Identity<string>.Bind( Identity<string>.Unit("some string"), s => Identity<string>.Unit( s + " was processed by identity monad.")).Value That of course is seriously ugly. Note that the operation is responsible for re-boxing its result. That is a part of strict monads that I don’t quite get and I’ll take the liberty to lift that strange constraint in the next examples. To make this more readable and easier to use, let’s build a few extension methods: public static class IdentityExtensions { public static Identity<T> ToIdentity<T>(this T value) { return new Identity<T>(value); } public static Identity<U> Bind<T, U>( this Identity<T> argument, Func<T, U> operation) { return operation(argument.Value).ToIdentity(); } } With those, we can rewrite our code as follows: "some string".ToIdentity() .Bind(s => s + " was processed by monad extensions.") .Bind(s => s + " And it's chainable...") .Value; This is considerably simpler but still retains the qualities of a monad. But it is still pointless. Let’s look at a more useful example, the state monad, which is basically a monad where the boxes have a label. It’s useful to perform operations on arbitrary objects that have been enriched with an attached state object. public class Stateful<TValue, TState> { public Stateful(TValue value, TState state) { Value = value; State = state; } public TValue Value { get; private set; } public TState State { get; set; } } public static class StateExtensions { public static Stateful<TValue, TState> ToStateful<TValue, TState>( this TValue value, TState state) { return new Stateful<TValue, TState>(value, state); } public static Stateful<TResult, TState> Execute<TValue, TState, TResult>( this Stateful<TValue, TState> argument, Func<TValue, TResult> operation) { return operation(argument.Value) .ToStateful(argument.State); } } You can get a stateful version of any object by calling the ToStateful extension method, passing the state object in. You can then execute ordinary operations on the values while retaining the state: var statefulInt = 3.ToStateful("This is the state"); var processedStatefulInt = statefulInt .Execute(i => ++i) .Execute(i => i * 10) .Execute(i => i + 2); Console.WriteLine("Value: {0}; state: {1}", processedStatefulInt.Value, processedStatefulInt.State); This monad differs from the identity by enriching the boxes. There is another way to give value to the monad, which is to enrich the processing. An example of that is the writer monad, which can be typically used to log the operations that are being performed by the monad. Of course, the richest monads enrich both the boxes and the processing. That’s all for today. I hope with this you won’t have to go through the same process that I did to understand monads and that you haven’t gone into concept overload like I did. Next time, we’ll examine some examples that you already know but we will shine the monadic light, hopefully illuminating them in a whole new way. Realizing that this pattern is actually in many places but mostly unnoticed is what will enable the truly casual “oh, yes, that’s a monad” comments. Here’s the code for this article: http://weblogs.asp.net/blogs/bleroy/Samples/Monads.zip The Wikipedia article on monads: http://en.wikipedia.org/wiki/Monads_in_functional_programming This article was invaluable for me in understanding how to express the canonical monads in C# (interesting Linq stuff in there): http://blogs.msdn.com/b/wesdyer/archive/2008/01/11/the-marvels-of-monads.aspx

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• SQL Server Installation Checklist

  - by Jonathan Kehayias

  The other night I was asked on Twitter by Todd McDonald (Twitter), for a build list for SQL Server 2005 and 2008.  My initial response was to provide a link to the SQL Server Build List Blog , which documents all of the builds of SQL Server and provides links to the KB articles associated with the builds.  However, this wasn’t what Todd was after, he actually wanted a reference for an installation checklist for SQL Server.  I have a number of these that I use in my job, and they vary...(read more)

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• Why do you need float/double?

  - by acidzombie24

  I was watching http://www.joelonsoftware.com/items/2011/06/27.html and laughed at Jon Skeet joke about 0.3 not being 0.3. I personally never had problems with floats/decimals/doubles but then I remember I learned 6502 very early and never needed floats in most of my programs. The only time I used it was for graphics and math where inaccurate numbers were ok and the output was for the screen and not to be stored (in a db, file) or dependent on. My question is, where are places were you typically use floats/decimals/double? So I know to watch out for these gotchas. With money I use longs and store values by the cent, for speed of an object in a game I add ints and divide (or bitshift) the value to know if I need to move a pixel or not. (I made object move in the 6502 days, we had no divide nor floats but had shifts). So I was mostly curious.

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• Computer Science: Arts or Science?

  - by sunpech

  Various colleges and universities may offer a degree in Computer Science either as an Arts or a Science. What differences are there between the two? Would recruiters and those who conduct interviews favor one over the other? (Bachelor of Arts vs Bachelor of Sciences etc...) Update - Just wanted to add this link to Joel Spolsky's site to give a better frame of reference: BA or BS in Computer Science

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• Operator of the week - Assert

  - by Fabiano Amorim

  Well my friends, I was wondering how to help you in a practical way to understand execution plans. So I think I'll talk about the Showplan Operators. Showplan Operators are used by the Query Optimizer (QO) to build the query plan in order to perform a specified operation. A query plan will consist of many physical operators. The Query Optimizer uses a simple language that represents each physical operation by an operator, and each operator is represented in the graphical execution plan by an icon. I'll try to talk about one operator every week, but so as to avoid having to continue to write about these operators for years, I'll mention only of those that are more common: The first being the Assert. The Assert is used to verify a certain condition, it validates a Constraint on every row to ensure that the condition was met. If, for example, our DDL includes a check constraint which specifies only two valid values for a column, the Assert will, for every row, validate the value passed to the column to ensure that input is consistent with the check constraint. Assert  and Check Constraints: Let's see where the SQL Server uses that information in practice. Take the following T-SQL: IF OBJECT_ID('Tab1') IS NOT NULL   DROP TABLE Tab1 GO CREATE TABLE Tab1(ID Integer, Gender CHAR(1))  GO  ALTER TABLE TAB1 ADD CONSTRAINT ck_Gender_M_F CHECK(Gender IN('M','F'))  GO INSERT INTO Tab1(ID, Gender) VALUES(1,'X') GO To the command above the SQL Server has generated the following execution plan: As we can see, the execution plan uses the Assert operator to check that the inserted value doesn't violate the Check Constraint. In this specific case, the Assert applies the rule, 'if the value is different to "F" and different to "M" than return 0 otherwise returns NULL'. The Assert operator is programmed to show an error if the returned value is not NULL; in other words, the returned value is not a "M" or "F". Assert checking Foreign Keys Now let's take a look at an example where the Assert is used to validate a foreign key constraint. Suppose we have this  query: ALTER TABLE Tab1 ADD ID_Genders INT GO  IF OBJECT_ID('Tab2') IS NOT NULL   DROP TABLE Tab2 GO CREATE TABLE Tab2(ID Integer PRIMARY KEY, Gender CHAR(1))  GO  INSERT INTO Tab2(ID, Gender) VALUES(1, 'F') INSERT INTO Tab2(ID, Gender) VALUES(2, 'M') INSERT INTO Tab2(ID, Gender) VALUES(3, 'N') GO  ALTER TABLE Tab1 ADD CONSTRAINT fk_Tab2 FOREIGN KEY (ID_Genders) REFERENCES Tab2(ID) GO  INSERT INTO Tab1(ID, ID_Genders, Gender) VALUES(1, 4, 'X') Let's look at the text execution plan to see what these Assert operators were doing. To see the text execution plan just execute SET SHOWPLAN_TEXT ON before run the insert command. |--Assert(WHERE:(CASE WHEN NOT [Pass1008] AND [Expr1007] IS NULL THEN (0) ELSE NULL END))      |--Nested Loops(Left Semi Join, PASSTHRU:([Tab1].[ID_Genders] IS NULL), OUTER REFERENCES:([Tab1].[ID_Genders]), DEFINE:([Expr1007] = [PROBE VALUE]))           |--Assert(WHERE:(CASE WHEN [Tab1].[Gender]<>'F' AND [Tab1].[Gender]<>'M' THEN (0) ELSE NULL END))           |    |--Clustered Index Insert(OBJECT:([Tab1].[PK]), SET:([Tab1].[ID] = RaiseIfNullInsert([@1]),[Tab1].[ID_Genders] = [@2],[Tab1].[Gender] = [Expr1003]), DEFINE:([Expr1003]=CONVERT_IMPLICIT(char(1),[@3],0)))           |--Clustered Index Seek(OBJECT:([Tab2].[PK]), SEEK:([Tab2].[ID]=[Tab1].[ID_Genders]) ORDERED FORWARD) Here we can see the Assert operator twice, first (looking down to up in the text plan and the right to left in the graphical plan) validating the Check Constraint. The same concept showed above is used, if the exit value is "0" than keep running the query, but if NULL is returned shows an exception. The second Assert is validating the result of the Tab1 and Tab2 join. It is interesting to see the "[Expr1007] IS NULL". To understand that you need to know what this Expr1007 is, look at the Probe Value (green text) in the text plan and you will see that it is the result of the join. If the value passed to the INSERT at the column ID_Gender exists in the table Tab2, then that probe will return the join value; otherwise it will return NULL. So the Assert is checking the value of the search at the Tab2; if the value that is passed to the INSERT is not found  then Assert will show one exception. If the value passed to the column ID_Genders is NULL than the SQL can't show a exception, in that case it returns "0" and keeps running the query. If you run the INSERT above, the SQL will show an exception because of the "X" value, but if you change the "X" to "F" and run again, it will show an exception because of the value "4". If you change the value "4" to NULL, 1, 2 or 3 the insert will be executed without any error. Assert checking a SubQuery: The Assert operator is also used to check one subquery. As we know, one scalar subquery can't validly return more than one value: Sometimes, however, a  mistake happens, and a subquery attempts to return more than one value . Here the Assert comes into play by validating the condition that a scalar subquery returns just one value. Take the following query: INSERT INTO Tab1(ID_TipoSexo, Sexo) VALUES((SELECT ID_TipoSexo FROM Tab1), 'F')    INSERT INTO Tab1(ID_TipoSexo, Sexo) VALUES((SELECT ID_TipoSexo FROM Tab1), 'F')    |--Assert(WHERE:(CASE WHEN NOT [Pass1016] AND [Expr1015] IS NULL THEN (0) ELSE NULL END))        |--Nested Loops(Left Semi Join, PASSTHRU:([tempdb].[dbo].[Tab1].[ID_TipoSexo] IS NULL), OUTER REFERENCES:([tempdb].[dbo].[Tab1].[ID_TipoSexo]), DEFINE:([Expr1015] = [PROBE VALUE]))              |--Assert(WHERE:([Expr1017]))             |    |--Compute Scalar(DEFINE:([Expr1017]=CASE WHEN [tempdb].[dbo].[Tab1].[Sexo]<>'F' AND [tempdb].[dbo].[Tab1].[Sexo]<>'M' THEN (0) ELSE NULL END))              |         |--Clustered Index Insert(OBJECT:([tempdb].[dbo].[Tab1].[PK__Tab1__3214EC277097A3C8]), SET:([tempdb].[dbo].[Tab1].[ID_TipoSexo] = [Expr1008],[tempdb].[dbo].[Tab1].[Sexo] = [Expr1009],[tempdb].[dbo].[Tab1].[ID] = [Expr1003]))              |              |--Top(TOP EXPRESSION:((1)))              |                   |--Compute Scalar(DEFINE:([Expr1008]=[Expr1014], [Expr1009]='F'))              |                        |--Nested Loops(Left Outer Join)              |                             |--Compute Scalar(DEFINE:([Expr1003]=getidentity((1856985942),(2),NULL)))              |                             |    |--Constant Scan              |                             |--Assert(WHERE:(CASE WHEN [Expr1013]>(1) THEN (0) ELSE NULL END))              |                                  |--Stream Aggregate(DEFINE:([Expr1013]=Count(*), [Expr1014]=ANY([tempdb].[dbo].[Tab1].[ID_TipoSexo])))             |                                       |--Clustered Index Scan(OBJECT:([tempdb].[dbo].[Tab1].[PK__Tab1__3214EC277097A3C8]))              |--Clustered Index Seek(OBJECT:([tempdb].[dbo].[Tab2].[PK__Tab2__3214EC27755C58E5]), SEEK:([tempdb].[dbo].[Tab2].[ID]=[tempdb].[dbo].[Tab1].[ID_TipoSexo]) ORDERED FORWARD)  You can see from this text showplan that SQL Server as generated a Stream Aggregate to count how many rows the SubQuery will return, This value is then passed to the Assert which then does its job by checking its validity. Is very interesting to see that  the Query Optimizer is smart enough be able to avoid using assert operators when they are not necessary. For instance: INSERT INTO Tab1(ID_TipoSexo, Sexo) VALUES((SELECT ID_TipoSexo FROM Tab1 WHERE ID = 1), 'F') INSERT INTO Tab1(ID_TipoSexo, Sexo) VALUES((SELECT TOP 1 ID_TipoSexo FROM Tab1), 'F')  For both these INSERTs, the Query Optimiser is smart enough to know that only one row will ever be returned, so there is no need to use the Assert. Well, that's all folks, I see you next week with more "Operators". Cheers, Fabiano

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• How to make and render a simple game just with 3d max?

  - by Sina

  I want to make a simple EXE file, where there is one object in the scene and the user can rotate that object by using arrow keys (or mouse). Is there any way in which I don't have to use a game engine and do it only using 3dsmax script? Cause there is a special renderer I want to use, which is V-Ray a kind of renderer which provides 3D images for 3D glasses. I am not good at making games and engines so I want to know if I can do it only with 3dsmax scripts?

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