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  • about null values!

    - by user329820
    Hi I have a question that if we declare a variable and then do not set it explicitly to null value then it would be null outomatically ,i mean that the below code will return true or false ? thanks DECLARE @val CHAR(4) If @val = NULL

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  • How do you create a transaction that spans multiple statements in Python with MySQLdb?

    - by Fast Fish
    I know that with an InnoDB table, transactions are autocommit, however I understand that to mean for a single statement? For example, I want to check if a user exists in a table, and then if it doesn't, create it. However there lies a race condition. I believe using a transaction prior to doing the select, will ensure that the table remains untouched until the subsequent insert, and the transaction is committed. How can you do this with MySQLdb and Python?

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  • is it safe to call "plink.exe" in an application

    - by EBAGHAKI
    i want to use "plink.exe -u username -pw securepassword" on my windows visual c++ program. will username and password remain safe while calling this command? I mean can a hacker steal or sniff the username and password? (consider hacker can't get to the password directly from the exe file)

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  • Parallel Task Library WaitAny Design

    - by colithium
    I've just begun to explore the PTL and have a design question. My Scenario: I have a list of URLs that each refer to an image. I want each image to be downloaded in parallel. As soon as at least one image is downloaded, I want to execute a method that does something with the downloaded image. That method should NOT be parallelized -- it should be serial. I think the following will work but I'm not sure if this is the right way to do it. Because I have separate classes for collecting the images and for doing "something" with the collected images, I end up passing around an array of Tasks which seems wrong since it exposes the inner workings of how images are retrieved. But I don't know a way around it. In reality there is more to both of these methods but that's not important for this. Just know that they really shouldn't be lumped into one large method that both retrieves and does something with the image. Task<Image>[] downloadTasks = collector.RetrieveImages(listOfURLs); for (int i = 0; i < listOfURLs.Count; i++) { //Wait for any of the remaining downloads to complete int completedIndex = Task<Image>.WaitAny(downloadTasks); Image completedImage = downloadTasks[completedIndex].Result; //Now do something with the image (this "something" must happen serially) } /////////////////////////////////////////////////// public Task<Image>[] RetrieveImages(List<string> urls) { Task<Image>[] tasks = new Task<Image>[urls.Count]; int index = 0; foreach (string url in urls) { string lambdaVar = url; //Required... Bleh tasks[index] = Task<Image>.Factory.StartNew(() => { using (WebClient client = new WebClient()) { //TODO: Replace with live image locations string fileName = String.Format("{0}.png", i); client.DownloadFile(lambdaVar, Path.Combine(Application.StartupPath, fileName)); } return Image.FromFile(Path.Combine(Application.StartupPath, fileName)); }, TaskCreationOptions.LongRunning | TaskCreationOptions.AttachedToParent); index++; } return tasks; }

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  • Using PUT/POST/DELETE with JSONP and jQuery

    - by ryanzec
    I am working on creating a RESTful API that supports cross-domain requests, JSON/JSONP support, and the main HTTP method (PUT/GET/POST/DELETE). Now while will be easy to accessing this API through server side code , it would nice to exposed it to javascript. From what I can tell, when doing a JSONP requests with jQuery, it only supports the GET method. Is there a way to do a JSONP request using POST/PUT/DELETE? Ideally I would like a way to do this from within jQuery (through a plugin if the core does not support this), but I will take a plain javascript solution too. Any links to working code or how to code it would be helpful, thanks.

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  • Spring 3 MVC : problem with form:errors and bindingresult

    - by Maxime ARNSTAMM
    Hi, I want to validate my inputs but i can't make it work : nothing appear on the page. My project is in java 5, so no JSR303 (@Valid). My only solution, if i'm not mistaken, is to use BindingResult. My controller : @Controller public class MyController { @RequestMapping(method = RequestMethod.POST, value = "myPage.html") public void myHandler(MyForm myForm, BindingResult result, Model model) { result.reject("field1", "error message 1"); } } My jsp : <form:form commandName="myForm" method="post"> <label>Field 1 : </label> <form:input path="field1" /> <form:errors path="field1" /> <input type="submit" value="Post" /> </form:form> What am i missing ? Thanks !

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  • Error using MVCContrib TestHelper

    - by Brian McCord
    While trying to implement the second answer to a previous question, I am receiving an error. I have implemented the methods just as the post shows, and the first three work properly. The fourth one (HomeController_Delete_Action_Handler_Should_Redirect_If_Model_Successfully_Delete) gives this error: Could not find a parameter named 'controller' in the result's Values collection. If I change the code to: actual .AssertActionRedirect() .ToAction("Index"); it works properly, but I don't like the "magic string" in there and prefer to use the lambda method that the other poster used. My controller method looks like this: [HttpPost] public ActionResult Delete(State model) { try { if( model == null ) { return View( model ); } _stateService.Delete( model ); return RedirectToAction("Index"); } catch { return View( model ); } } What am I doing wrong?

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  • Rails way for querying join table in has_and_belongs_to_many

    - by Michelle
    I have a user model and a role model with a has_and_belongs_to_many reliationship. The join table is roles_users (two columns - the PK of the user and the role) and has no corresponding model. I want to have a method that returns all users with a given role. In SQL that'd be something like SELECT u.id FROM role.r, roles_users ru WHERE r.role_id = #{role.id} AND r.role_id = ru.role_id I see that Rails' activerecord has a find_by_sql method, but it's only expecting one results to be returned. What is the "Rails Way" to give me a list of users with a given role e.g. def self.find_users_with_role(role) users = [] users << # Some ActiveRecord magic or custom code here..? end

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  • Code Golf: Print the entire "12 Days of Christmas" song in the fewest lines of code.

    - by fizzer
    Print all 12 verses of the popular holiday song. By 12 verses I mean the repetition of each line as is sung in the song, ie Verse One: On the first day of Christmas my true love gave to me a partridge in a pear tree. Verse Two On the second day of Christmas my true love gave to me two turtle doves and a partridge in a pear tree. ... Verse N: On the nth day of Christmas my true love gave to me (Verse N-1 without the first line) (line added in verse N)

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  • An analog of String.Join(string, string[]) for IEnumerable<T>

    - by abatishchev
    class String contains very useful method - String.Join(string, string[]). It creates a string from an array, separating each element of array with a symbol given. But general - it doesn't add a separator after the last element! I uses it for ASP.NET coding for separating with "<br />" or Environment.NewLine. So I want to add an empty row after each row in asp:Table. What method of IEnumerable<TableRow> can I use for the same functionality?

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  • supress warning for generated c# code

    - by soren.enemaerke
    I have turned on "Treat warnings as errors" for my VS project which mean that I get errors for missing documentation (nice reminder for this particular project). However, part of the code is generated by a custom tool which does not insert xml documentation so I'm looking for away to ignore the missing xml documentation for the generated code only, not for the entire project. I have no influence on the actual file generated and cannot really insert anything in the file (as it is regenerated frequently by the tool) so I looking for something existing outside the generated file (the classes that are generated are partial, if that helps)

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  • How to run a jar file in hadoop

    - by Arihant
    I have created a jar file using the java file from this blog using following statements javac -classpath /usr/local/hadoop/hadoop-core-1.0.3.jar -d /home/hduser/dir Dictionary.java /usr/lib/jvm/jdk1.7.0_07/bin/jar cf Dictionary.jar /home/hduser/dir Now i have tried running this jar in hadoop by hit and trial of various commands 1hduser@ubuntu:~$ /usr/local/hadoop/bin/hadoop jar Dictionary.jar Output: Warning: $HADOOP_HOME is deprecated. RunJar jarFile [mainClass] args... 2.hduser@ubuntu:~$ /usr/local/hadoop/bin/hadoop jar Dictionary.jar Dictionary Output: Warning: $HADOOP_HOME is deprecated. Exception in thread "main" java.lang.ClassNotFoundException: Dictionary at java.net.URLClassLoader$1.run(URLClassLoader.java:366) at java.net.URLClassLoader$1.run(URLClassLoader.java:355) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:354) at java.lang.ClassLoader.loadClass(ClassLoader.java:423) at java.lang.ClassLoader.loadClass(ClassLoader.java:356) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:264) at org.apache.hadoop.util.RunJar.main(RunJar.java:149) How can i run the jar in hadoop? I have the right DFS Locations as per needed by my program.

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  • Cocoa NSWindow not updating with data

    - by Matt S.
    I have an NSWindow that shows up when you click either of two items (both from an NSTableView). I have a setter method that tells the window what information to display. This all works perfectly, until it comes time to display the data in the window. If I cause the window to display from one tableview, then try to have it display the new data from another it doesn't do it, it keeps the old data on. I am using the exact same method to get and display the data from both possible ways to have the window show up, and the data is changing correctly. To display the window I'm using [mywindow makeKeyAndOrderFront:self];

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  • Visual Studio 2010 + Resharper Tools|Options|Environment|Fonts and Colors

    - by Gerard
    About fonts and colors in the VS2010 C# text editor with Resharper installed. In the following method: public void Method() { var lis = new System.Collections.ArrayList(); var exc = new System.NotImplementedException(); } ArrayList gets another color as NotImplementedException in the VS2010 text editor, because I edited the color scheme. What would be the difference in these kinds of types so that the color scheme handles them differently? Note that I have Resharper installed but I also tried almost all Resharper entries. I would like to have the ame color for both, but the color of the NotImplementedException type seems immutable.

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  • Please help, now I have a matrix, I want use Combination algorithm to generate a array for length 6

    - by user313429
    The first thanks a lot for your help , the following is my matrix, I want to implement combination algorithm between multiple arrays in LINQ for this matrix. int[,] cj = { { 10, 23, 16, 20 }, { 22, 13, 1, 33 }, { 7, 19, 31, 12 }, { 30, 14, 21, 4 }, { 2, 29, 32, 6 }, { 18, 26, 17, 8 }, { 25, 11, 5, 28 }, { 24, 3, 15, 27 } }; other: public static IEnumerable<IEnumerable<T>> Combinations<T>(this IEnumerable<T> elements, int k) { return k == 0 ? new[] { new T[0] } : elements.SelectMany((e, i) => elements.Skip(i + 1).**Combinations**(k - 1).Select(c => (new[] { e }).Concat(c))); } The above method has a error in my project, System.Collections.Generic.IEnumerable' does not contain a definition for 'Combinations' and no extension method 'Combinations' accepting a first argument of type 'System.Collections.Generic.IEnumerable' could be found (are you missing a using directive or an assembly reference? I use .Net Framework3.5, what is the reason it?

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  • What's the best way to unit test code that generates random output?

    - by Flynn1179
    Specifically, I've got a method picks n items from a list in such a way that a% of them meet one criterion, and b% meet a second, and so on. A simplified example would be to pick 5 items where 50% have a given property with the value 'true', and 50% 'false'; 50% of the time the method would return 2 true/3 false, and the other 50%, 3 true/2 false. Statistically speaking, this means that over 100 runs, I should get about 250 true/250 false, but because of the randomness, 240/260 is entirely possible. What's the best way to unit test this? I'm assuming that even though technically 300/200 is possible, it should probably fail the test if this happens. Is there a generally accepted tolerance for cases like this, and if so, how do you determine what that is?

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  • Custom DataGridView column sort based on Value not Formatted value

    - by Dan Neely
    I have a custom DGV cell I'm using to display the contents of MyType objects. To control how they're being formatted I'm overriding the GetFormattedValue() and FormattedvalueType methods of DataGridViewTextBoxCell because in this case I don't want to use the default ToString() method. The problem is that when I do this the DGV is sorting the column by the string in FormattedValue instead of by Value. I'm not seeing a method I can override to change the sort behavior of the column. While I know I can, I don't want to have to write custom Sort mthods for the DGVs themselves because I'm using this in multiple DGV's.

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  • How to apply Data Mining (Association Rule) to a huge database ?

    - by stckvrflw
    Hello What I want to do is to apply Association method of data mining on my SQL Server 2000 database. Association rule is something like "finding the most frequent items that appear together in database." For those who don't know or who want to remember what is association method is like, take a look at this presentation about Association rule in Data Mining. www.authorstream.com/Presentation/a.besimi-233030-data-mining-intro-seeu-education-ppt-powerpoint 17th slide gives a nice example of applying association rule on a database. So Can you help me about how should I write my SQL codes (If they will be sufficient of course) Thanks.

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