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  • User has many computers, computers have many attributes in different tables, best way to JOIN?

    - by krismeld
    I have a table for users: USERS: ID | NAME | ---------------- 1 | JOHN | 2 | STEVE | a table for computers: COMPUTERS: ID | USER_ID | ------------------ 13 | 1 | 14 | 1 | a table for processors: PROCESSORS: ID | NAME | --------------------------- 27 | PROCESSOR TYPE 1 | 28 | PROCESSOR TYPE 2 | and a table for harddrives: HARDDRIVES: ID | NAME | ---------------------------| 35 | HARDDRIVE TYPE 25 | 36 | HARDDRIVE TYPE 90 | Each computer can have many attributes from the different attributes tables (processors, harddrives etc), so I have intersection tables like this, to link the attributes to the computers: COMPUTER_PROCESSORS: C_ID | P_ID | --------------| 13 | 27 | 13 | 28 | 14 | 27 | COMPUTER_HARDDRIVES: C_ID | H_ID | --------------| 13 | 35 | So user JOHN, with id 1 owns computer 13 and 14. Computer 13 has processor 27 and 28, and computer 13 has harddrive 35. Computer 14 has processor 27 and no harddrive. Given a user's id, I would like to retrieve a list of that user's computers with each computers attributes. I have figured out a query that gives me a somewhat of a result: SELECT computers.id, processors.id AS p_id, processors.name AS p_name, harddrives.id AS h_id, harddrives.name AS h_name, FROM computers JOIN computer_processors ON (computer_processors.c_id = computers.id) JOIN processors ON (processors.id = computer_processors.p_id) JOIN computer_harddrives ON (computer_harddrives.c_id = computers.id) JOIN harddrives ON (harddrives.id = computer_harddrives.h_id) WHERE computers.user_id = 1 Result: ID | P_ID | P_NAME | H_ID | H_NAME | ----------------------------------------------------------- 13 | 27 | PROCESSOR TYPE 1 | 35 | HARDDRIVE TYPE 25 | 13 | 28 | PROCESSOR TYPE 2 | 35 | HARDDRIVE TYPE 25 | But this has several problems... Computer 14 doesnt show up, because it has no harddrive. Can I somehow make an OUTER JOIN to make sure that all computers show up, even if there a some attributes they don't have? Computer 13 shows up twice, with the same harddrive listet for both. When more attributes are added to a computer (like 3 blocks of ram), the number of rows returned for that computer gets pretty big, and it makes it had to sort the result out in application code. Can I somehow make a query, that groups the two returned rows together? Or a query that returns NULL in the h_name column in the second row, so that all values returned are unique? EDIT: What I would like to return is something like this: ID | P_ID | P_NAME | H_ID | H_NAME | ----------------------------------------------------------- 13 | 27 | PROCESSOR TYPE 1 | 35 | HARDDRIVE TYPE 25 | 13 | 28 | PROCESSOR TYPE 2 | 35 | NULL | 14 | 27 | PROCESSOR TYPE 1 | NULL | NULL | Or whatever result that make it easy to turn it into an array like this [13] => [P_NAME] => [0] => PROCESSOR TYPE 1 [1] => PROCESSOR TYPE 2 [H_NAME] => [0] => HARDDRIVE TYPE 25 [14] => [P_NAME] => [0] => PROCESSOR TYPE 1

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  • What is the best method for implementing mouse wheel activity in Delph1 VCL forms?

    - by Brian Frost
    As a long time user of Delphi 7, I've rolled my own mouse wheel handling in a few controls but lately I've noticed that some recent applications only need the mouse cursor to be placed over a control (e.g a list box or tree view) for the mouse wheel activity to cause that control to scroll. This feels nice (as opposed to having to click focus a control before it responds to the wheel. Now I've moved to Delphi 2010 I'm wondering what is the 'correct' behaviour? And what can I use in Delphi that avoids me having to bodge this with my own solutions now? Thanks.

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  • Whats the best data-structure for storing 2-tuple (a, b) which support adding, deleting tuples and c

    - by bhups
    Hi So here is my problem. I want to store 2-tuple (key, val) and want to perform following operations: - keys are strings and values are Integers - multiple keys can have same value - adding new tuples - updating any key with new value (any new value or updated value is greater than the previous one, like timestamps) - fetching all the keys with values less than or greater than given value - deleting tuples. Hash seems to be the obvious choice for updating the key's value but then lookups via values will be going to take longer (O(n)). The other option is balanced binary search tree with key and value switched. So now lookups via values will be fast (O(lg(n))) but updating a key will take (O(n)). So is there any data-structure which can be used to address these issues? Thanks.

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  • What's the best way to store Logon User information for Web Application?

    - by Morgan Cheng
    I was once in a project of web application developed on ASP.NET. For each logon user, there is an object (let's call it UserSessionObject here) created and stored in RAM. For each HTTP request of given user, matching UserSessoinObject instance is used to visit user state information and connection to database. So, this UserSessionObject is pretty important. This design brings several problems found later: 1) Since this UserSessionObject is cached in ASP.NET memory space, we have to config load balancer to be sticky connection. That is, HTTP request in single session would always be sent to one web server behind. This limit scalability and maintainability. 2) This UserSessionObject is accessed in every HTTP request. To keep the consistency, there is a exclusive lock for the UserSessionObject. Only one HTTP request can be processed at any given time because it must to obtain the lock first. The performance and response time is affected. Now, I'm wondering whether there is better design to handle such logon user case. It seems Sharing-Nothing-Architecture helps. That means long user info is retrieved from database each time. I'm afraid that would hurt performance. Is there any design pattern for long user web app? Thanks.

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  • Load XML file into object. Best method?

    - by Cypher
    Hello, We are receiving an XML file from our client. I want to load the data from this file into a class, but am unsure about which way to go about it. I have an XSD to defining what is expected in the XML file, so therefore i can easily validate the XML file. Can i use the XSD file to load the data into a POCO, using some sort of serialization? The other way i was thinking was to load the xml into a XMLDocument and use XPath to populate each property in my class. Cheers for any advice

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  • Which will be the best query OR there is an another one?

    - by serhan
    SELECT k.id,k.adsoyad, COUNT(DISTINCT(e.id)) as iletisimbilgisisay, COUNT(DISTINCT(f.id)) AS ilangonderensay, COUNT(DISTINCT(g.id)) AS emlaksahibisay, isNULL(MAX(eb.yonetici_kisi),0) AS yoneticiid FROM dbo.kisiler k LEFT OUTER JOIN dbo.emlaklar e ON e.iletisimbilgisi=k.id LEFT OUTER JOIN dbo.emlaklar f ON f.ilangonderen=k.id LEFT OUTER JOIN dbo.emlaklar g ON g.emlaksahibi=k.id LEFT OUTER JOIN dbo.emlakcibilgileri eb ON eb.yonetici_kisi=k.id GROUP BY k.id,k.adsoyad ORDER BY yoneticiid DESC, iletisimbilgisisay DESC, ilangonderensay DESC total execution time (above) 28 SELECT id,adsoyad, (select COUNT(id) FROM dbo.emlaklar WHERE iletisimbilgisi=k.id) AS iletisimbilgisisay, (select COUNT(id) FROM dbo.emlaklar WHERE emlaksahibi=k.id) AS emlaksahibisay, (select COUNT(id) FROM dbo.emlaklar WHERE ilangonderen=k.id) AS ilangonderensay, (Select isNULL(MAX(id),0) FROM dbo.emlakcibilgileri WHERE yonetici_kisi=k.id) AS yoneticiid FROM dbo.kisiler k total execution time 4 my tables are emlaklar: id int, ilangonderen int,iletisimbilgisi int,emlaksahibi int kisiler: id int,kisiadi emlakcibilgileri: id int,yonetici_kisi int,firma and ilangonderen,iletisimbilgisi,emlaksahibi,yonetici_kisi => kisiler.id

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  • Best evidence to offer a sandboxed appdomain for a C# evaluator.

    - by scope-creep
    I have a c# evaluator which uses the (I think) the .Net 4 new simplified sandboxed appdomain model to host the c# assembly, with remoting doing the rest. The call to create the appdomain is Evidence ev = new Evidence(); ev.AddHostEvidence(new Zone(SecurityZone.Trusted)); PermissionSet pset = SecurityManager.GetStandardSandbox(ev); AppDomainSetup ads = new AppDomainSetup(); ads.ApplicationBase = "C:\\Sandbox"; // Create the sandboxed domain. AppDomain sandbox = AppDomain.CreateDomain( "Sandboxed Domain", ev, ads, pset, null); The c# eval is embedded in a server app, but I don't want give the sandbox to much control unless it bo bo's the caller. What i'm looking for is regarding some clarification as to what to provide as Evidence from the caller. I'm looking for advice and guidance. Any help would be appreciated.

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  • what is the best and valid way for cross browser min-height?

    - by metal-gear-solid
    for #main-content I don't want to give any fix height because content can be long and short but if content is short then it should take minimum height 500px. i need compatibility in all browser. Is thery any w3c valid and cross browser way without using !important because i read !important should not be used In conclusion, don’t use the !important declaration unless you’ve tried everything else first, and keep in mind any drawbacks. If you do use it, it would probably make sense, if possible, to put a comment in your CSS next to any styles that are being overridden, to ensure better code maintainability. I tried to cover everything significant in relation to use of the !important declaration, so please offer comments if you think there’s anything I’ve missed, or if I’ve misstated anything, and I’ll be happy to make any needed corrections. http://www.impressivewebs.com/everything-you-need-to-know-about-the-important-css-declaration/

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  • What's the best technique to protect my framework from visitors who are not logged in?

    - by Hermet
    First of all, I would like to say that I have used the search box looking for a similar question and was unsuccessful, maybe because of my poor english skills. I have a a 'homemade' framework. I have certain PHP files that must only be visible for the admin. The way I currently do this is check within every single page to see if a session has been opened. If not, the user gets redirected to a 404 page, to seem like the file which has been requested doesn't exist. I really don't know if this is guaranteed to work or if there's a better and more safe way because I'm currently working with kind of confidential data that should never become public. Could you give me some tips? Or leave a link where I could find some? Thank you very much, and again excuse me for kicking the dictionary. EDIT What I usually write in the top of each file is something like this <?php include("sesion.php"); $rs=comprueba(); //'check' if ($rs==1) { ?> And then, at the end <?php } ?> Is it such a butched job, isn't it? EDIT Let's say I have a customers list in a file named customers.php That file may be currently on http://www.mydomain.com/admin/customers.php and it must only be visible for the admin user. Once the admin user has been logged in, I create a session variable. That variable is what I check on the top of each page, and if it exists, the customers list is shown. If not, the user gets redirected to the 404 page. Thank you for your patience. I really appreciate.

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  • What's the best way to mix Ruby and other languages? (Especially C++)

    - by Andy
    Hi, I'm learning Ruby, and I'm starting to play with building extensions in C. I have Programming Ruby The Pragmatic Programmers' Guide and so I can follow that for the basic nuts and bolts. What I was wondering is if there already existed some nifty frameworks/whatever to help interoperability between Ruby and other languages, with C++ being the most important for me. I've tried googling, but the results focus on language comparisons, rather than language interoperability. TIA, Andy

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  • Best way to insert items from a Derived class's constructor into a Base class's private std::vector?

    - by Will
    I have these classes: class Base { ... private: std::vector<X> v; }; class Derived { Derived(X*, int n); } where the constructor of Derived is passed an array of item Xs, which I need to insert into my vector v in the Base class. (X is a smart pointer) Currently I see two ways to do this: 1) Create a function in Base: InsertItem(X*) that will insert an item into the vector. 2) Create a vector in Derived that contains the full list, then get it into Base by moving the entire vector. I dont see any advantages to #2, but was wondering if #1 was a good solution, or if there are better ways to do this. Thanks!

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  • If don't own proprietary database engine, what is best way to convert database to mysql?

    - by John Robertson
    I work for a very small company. I was recently faced with the question of whether there is a good way to convert a proprietary database to a MySQL database without owning the proprietary database engine e.g. if one is given a large oracle database file (or choose your favorite proprietary database engine format), but doesn't have a license for the oracle database engine, is there a good, perfectly reliable way to convert it to a MySQL database format that can be read with the MySQL database engine? My question is very vague as to which proprietary format is the source just because there would be multiple sources and it looks like they would be "various and sundry". My suspicion is that there is no perfectly reliable way, especially for a wide variety of proprietary databases. If there are a few proprietary formats for which this is possible, I would still be interested in knowing, though "various and sundry" is probably the real issue. Minimizing cost, effort and correct conversion are key so I think this is probably is the not possible list. -John

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  • What's the best way to identify subdomains by PHP dynamically?

    - by kavoir.com
    I have configured the wildcard DNS of *.mydomain.com and it's all working properly. My question is which of these should I rely on identifying client subdomain requests? $_SERVER["HTTP_HOST"] $_SERVER["SERVER_NAME"] $_SERVER["SCRIPT_URI"] They all seem to contain the subdomain part I want but after reading this article by Chris: http://shiflett.org/blog/2005/feb/more-on-filtering-input-and-escaping-output, I'm lost at see and there appears to be no safe way to do this? Any idea on accomplishing this task securely?

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  • What's the best way to pass a PHP variable to Javascript?

    - by Gregory Bolkenstijn
    I currently echo certain variables in hidden input fields and read them out with Javascript whenever I need them. Me and a colleague are now thinking of generating an extra Javascript file with PHP which only contains all variables for Javascript. This way the variables already exist and there is no extra code in the HTML. What are good ways to pass variables from PHP to Javascript? And how does our solution sound?

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  • Best way to test if a generic type is a string? (c#)

    - by Rex M
    I have a generic class that should allow any type, primitive or otherwise. The only problem with this is using default(T). When you call default on a value type or a string, it initializes it to a reasonable value (such as empty string). When you call default(T) on an object, it returns null. For various reasons we need to ensure that if it is not a primitive type, then we will have a default instance of the type, not null. Here is attempt 1: T createDefault() { if(typeof(T).IsValueType) { return default(T); } else { return Activator.CreateInstance<T>(); } } Problem - string is not a value type, but it does not have a parameterless constructor. So, the current solution is: T createDefault() { if(typeof(T).IsValueType || typeof(T).FullName == "System.String") { return default(T); } else { return Activator.CreateInstance<T>(); } } But this feels like a kludge. Is there a nicer way to handle the string case?

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