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• How can an SQL query return data from multiple tables

  - by Fluffeh

  I would like to know how to get data from multiple tables in my database, what types of methods are there to do this, what are joins and unions and how are they different from one another? When should I use each one compared to the others? I am planning to use this in my (for example - PHP) application, but don't want to run multiple queries against the database, what options do I have to get data from multiple tables in a single query? Note: I am writing this as I would like to be able to link to a well written guide on the numerous questions that I constantly come across in the PHP queue, so I can link to this for further detail when I post an answer. The answers cover off the following: Part 1 - Joins and Unions Part 2 - Subqueries Part 3 - Tricks and Efficient Code

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• Can I correctly debug assemblies loaded with the 'AssemblyResolve' event?

  - by Thiado de Arruda

  I'm experimenting with the AppDomain's 'AssemblyResolve' event by hidding the depedencies for an executable file in another folder. The assemblies seem to beloading and executing fine, however debugging seems to be crazy, sometimes it hits my break points, sometimes it doesnt , and sometimes it hits the same code twice(It seems absurd but I'm sure the code is executing only once). I don't understanding how debuggers works but I guess it has something to do with the PDB files. Anyone got an idea of what might be happening and how can I fix it? Edit: Let me add that I'm calling methods on the dynamically loaded assemblies using reflection, sometimes the method I'm stepping over throws an exception that only pops at a later time.

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• UITableView cellForRowAtIndexPath occasionally not called?

  - by Tobster

  I'm developing a graphing application that on the main navigation/tab view displays a UIView that renders a graph using openGL. Beneath that view is a UITableView that displays the list of elements on the graph, and an add button. Occasionally, when the user clicks on another tab, and then returns to the graph view tab, the table view does not get redrawn. I have a [tableView reloadData] method being called in the navigation controllers' (also the table view's delegate and data source) viewDidAppear method. numberOfSectionsInTableView and numberOfRowsInSection get called, but cellForRowAtIndexPath does not despite both latter methods returning positive values. This is an intermittant problem, only happening some of the time, but it's not clear what (if anything) influences this. Does anyone have any ideas?

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• When I use WinForms (C#) designer in VS2010, it still generates code that StyleCop complains about.

  - by Hamish Grubijan

  Some problems that I recall (there may be more): Includes regions Does not use this. prefix for member variables and methods Includes comments like the one below ( having // by itself catches the eye of StyleCop) // // fileNameTextBox // If I make a change to the text, and then open the designer again, and screws up my previously perfected fruits of hard labor. How did / would you solve this problem? I heard but did not personally experience a similar problem with WPF. How did / would you fix that? Thanks.

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• Using adaptive step sizes with scipy.integrate.ode

  - by Mike

  The (brief) documentation for scipy.integrate.ode says that two methods (dopri5 and dop853) have stepsize control and dense output. Looking at the examples and the code itself, I can only see a very simple way to get output from an integrator. Namely, it looks like you just step the integrator forward by some fixed dt, get the function value(s) at that time, and repeat. My problem has pretty variable timescales, so I'd like to just get the values at whatever time steps it needs to evaluate to achieve the required tolerances. That is, early on, things are changing slowly, so the output time steps can be big. But as things get interesting, the output time steps have to be smaller. I don't actually want dense output at equal intervals, I just want the time steps the adaptive function uses.

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• Changing dalvik/libcore causes rebuilding the whole framework

  - by ZelluX

  I'm adding some interception routines to Dalvik libcore methods (e.g. file open method in libcore/luni/src/main/java/org/apache/harmony/luni/platform/OSFileSystem.java), which I think only changes basic sharing libraries. But to my surprise, every time I run make after modifications, it rebuilds nearly everything of the framework, such as Calculator application, W3C DOM parser, etc. It really takes time to build the framework after a small modification. I'm wondering if it is possible to reduce number of rebuilt components after modifying dalvik libcore? Thanks.

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• How to load an entity by a key other than primary key?

  - by stacker

  In a customized servlet (seam 2.1.2) this works fine TableNameHome tableNameHome = (TableNameHome) Component.getInstance( "tableNameHome " ); tableName entity = tableNameHome.getInstance(); entity.setXXX(); tableNameHome.persit(); However this one fails: entityManager = tableNameHome .getEntityManager(); Query query = entityManager.createQuery( "SELECT b FROM tablename b WHERE b.box_id = :key2nd" ); query.setParameter( "key2nd", value); List results = query.getResultList(); and leads to this error message: org.hibernate.hql.ast.QuerySyntaxException: tablename is not mapped [SELECT b FROM tablename b WHERE b.key2nd = :key2nd] In EJB 2.1 I could implement other finder-methods. EntityHome.find() searches only by primary key. What do I need to do in order to query by a different criteria than primary key?

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• How to deal with callback to your UIController after your UIController unloads?

  - by erotsppa

  Suppose your controller is a table view and one of the cells you are going off to do a length task (say download a thumbnail) to be viewed in the cell. Typically you would have the network call do a callback to your controller when it is done downloading. The callback can then reload the table or do some other form of UI update (hides a spinner etc). However, what if the controller is unloaded? Say the user navigated away from this controller and it got released? What happens? Will the callback still work despite the controller now not in memory? Also, if the callback operates on some objects (say the UITableView) what happens when the controller is deallocated? I suppose the controller can release all the objects and the callback would just be calling methods on nil to prevent crash. But is this the convention?

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• PHP: Class extends problem "Call to private method ... from context ..."

  - by sombe

  I have 3 classes in WordPress (the question itself is unrelated to it): class WP_Widget class Theme_Widget extends WP_Widget class Specific_Widget extends Theme_Widget Essentially Theme_Widget contains some extension functions to the basic WP_Widget. Inside Specific_Widget I call one of Theme_Widget's methods: class Specific_Widget { function __construct() { $this->some_method_that_belongs_to_Theme_Widget(); } } When I instantiate Specific_Widget, PHP throws a fatal error as follows: Fatal error: Call to private method Theme_Widget::some_method_that_belongs_to_Theme_Widget() from context 'Specific_Widget' in ... Do you have an idea as to how I can resolve this? This is the first time I've received this error from PHP. Could it be derive from WordPress itself?

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• Simultaneous private and public inheritance in C++

  - by gspr

  Suppose a class Y publicly inherits a class X. Is it possible for a class Z to privately inherit Y while publicly inheriting X? To make this clearer, suppose X defines public methods x1 and x2. Y inherits X, overrides x1 and provides a method y. Does C++ allow for a third class Z to subclass Y in such a way that Y's implementation of x1 and y are privately available to it, while the outside world only sees it inheriting X publicly, i.e. having only a single public method x2?

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• wav stopped working with AudioServices on my iPhone app?

  - by user157733

  I have a wav file that was working fine. It is played using the AudioServices methods. Suddenly it stopped working. The weird thing is if i change he wav file to a different one that works. Any idea what is going on? The non working sound is slightly longer (still <10seconds) but it was originally working so I just can't figure it out. Any suggestions of what to try would be most appreciated. Thanks :-)

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• Design guide-lines for writing a Typed SQL Statement API ?

  - by this. __curious_geek

  Last night I came up to sometihng intersting while designing my new project that brought me to ask this qustion here. My project is supposed to follow Table Gateway pattern using tradional ADO.Net datasets for data access. I don't want to write plain queries in my data-access classes. So I came up with an idea of writing a parser kindaa api that exposes objects and methods to generate queries on the move based on my domain objects. Later I want this api to hook up to my Business objects and provide Typed SQL generator api right on the business object instances. Any idea or references how can I do this ? This seems very wide to start with that I'm compelled take your opinions here. Does there anything already exists that can do this ?

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• Passing page control from jscript to pagemethod in the codebehind?

  - by brandonprry

  Hi, I am looking write a javascript method as such called when a dropdownlist changes value function GetStuff(sender, destID){ var dest = document.getElementById(destID); this.PageMethods.GetStuffs(sender, dest, null, null); } GetStuffs() is in the Codebehind as follows: [WebMethod] public static void GetStuffs(object sender, object dest) { DropDownList s = sender as DropDownList; DropDownList d = dest as DropDownList; d.Items.Add(new ListItem(s.SelectedValue)); } I have a break point set at the method and alerts in the GetStuff() jscript method fire up until the PageMethod call, at which nothing happens. I have set OnSuccess and OnFailure methods up with alerts and they don't get fired. Any thoughts? Am I doing something inherently wrong?

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• Where to reopen a class in RoR

  - by Jeriko

  I'm attempting to reopen the String class in rails and add a bunch more methods for my app to use. Writing the code isn't a problem - my question is rather about where this code should go. It doesn't make sense to me to reopen a class inside a different model file, because it really has nothing to do with any of the models specifically. I thought perhaps somewhere in config or lib would make sense, but I'm not particularly well versed with RoR yet. To summarize, where would be the most logical place to define class-modifying code?

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• In OCaml, how can I create an out_channel which writes to a string/buffer instead of a file on disk

  - by Tianyi Cui

  I have a function of type in_channel -> out_channel -> unit which will output something to an out_channel. Now I'd like to get its output as a string. Creating temporary files to write and read it back seems ugly, so how can I do that? Is there any other methods to create out_channel besides Pervasives.open_out family? Actually, this function implemented a repl. What I really need is to test it programmatically, so I'd like to first wrap it to a function of type string -> string. For creating the in_channel, it seems I can use Scanf.Scanning.from_string, but I don't know how to create the out_channel parameter.

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• Need help on how to setup my packages and projects in eclipse

  - by jax

  I am new to Java and am making a license generator. This is my current setup. com.example.licensegenerator.client (used by the client application) :LicenseLoader (no Main method) :LicenseDownloader (no Main method) com.example.licensegenerator.server.keys (used by the server) :ProductKeyGenerator(Main method) com.example.licensegenerator.server.license (used on the server also) :LicenseGenerator(Main method) com.example.licensegenerator.lib (Shared classes between client and server) :Contants (no main) Now I have a few questions. Is it OK to have multiple Main() methods in a single project? Will I be able to compile them to different .jar files? (In this case I need two different jars for the server) Is there a better way to setup the packages? And a totally unrelated question, with exceptions, is it better to handle them right then and there or throw them and let the main method catch them all (the program cannot recover if an error occurs)

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• Acceptable to have spaces before dot?

  - by Rudy

  What is the general opinion on the 2nd indentation method below. // Normal indentation a.Value = "foobar"; ab.Checked = false; foo.Value = "foobar"; foobar.Checked = true; // Spaces before the dot to align the properties/methods a .Value = "foobar"; ab .Checked = false; foo .Value = "foobar"; foobar.Checked = true; This should probably be a wiki, but I either don't have enough privileges or don't know how to change it.

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• Error Handling in Model (MVC)

  - by Andre

  I was wondering what the excepted standard is for handling errors in the Model. Currently I have 'setError' and 'getError' methods that's in use by all my Models. This means I'm only concerned with whether a call to a method in my Model is true or false. If it's false then I would use $this-model-getError() in my Controller. Additionally I'm contemplating setting up a separate file that contains all my errors. One file per model, also wanted to have thoughts on this.

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• Sharing base object with inheritance

  - by max

  I have class Base. I'd like to extend its functionality in a class Derived. I was planning to write: class Derived(Base): def __init__(self, base_arg1, base_arg2, derived_arg1, derived_arg2): super().__init__(base_arg1, base_arg2) # ... def derived_method1(self): # ... Sometimes I already have a Base instance, and I want to create a Derived instance based on it, i.e., a Derived instance that shares the Base object (doesn't re-create it from scratch). I thought I could write a static method to do that: b = Base(arg1, arg2) # very large object, expensive to create or copy d = Derived.from_base(b, derived_arg1, derived_arg2) # reuses existing b object but it seems impossible. Either I'm missing a way to make this work, or (more likely) I'm missing a very big reason why it can't be allowed to work. Can someone explain which one it is? [Of course, if I used composition rather than inheritance, this would all be easy to do. But I was hoping to avoid the delegation of all the Base methods to Derived through __getattr__.]

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• how to interpret testng console log message for passing tests?

  - by Kunal Cholera

  I ran testng tests for my test classes, I get the following three types of log output when I run the passing tests. I am using org.testng.AssertJUnit.assertTrue() methods in my tests. [testng] PASSED: testMethod1 on null(test.foo.bar.Class1) [testng] PASSED: testMethod2 on Default test name(test.foo.bar.jar.Class2) [testng] PASSED: testMethod3 Can any one please tell me why for some tests it says "on null" for some it says "on Default test name ... " and for some it does not say anything on the console output. Specifically I want to make it consistent message. Environment : linux Testng framework : 6.3.2beta please advise. thanks.

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• Best way to call other class view in iphone?

  - by aman-gupta

  Hi, Generally i call my other class view by creating a pointer of delegate and then call the other class by using its link as below:- First Way :- Mydelegate *ptr = (Mydelegate *)[[UIApplication sharedApplication]delegate]; [self.navigationController pushViewController:ptr.NextClasspointer animated:YES]; Second Way :- Create a pointer of that class which u want to call :-- NextClass *nextptr = [[NextClass alloc]initWithnibName:@"NextClass" bundle:nil]; [self.navigationController pushViewController:nextptr animated:YES]; [nextptr release]; nextptr = nil; These above two methods i generally used but my problem is that which one is best for big project so that my stack problem will be removed I mean memory issue will be solved.And is it necessary to release pointer in first and second case is the way i release is correct or wrong Please help me Thanks in Advance

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• How to handle feedback from background threads if the user uses the back button?

  - by Janusz

  I have the following problem: I have an Activity where a user can start a web search showing a new activity to show a progress bar until the results are shown. Now the user can either wait for the results or maybe think about the search parameters, hit the back button and triggering a new search. The search is running in an Async Task and therefor still running if the user hits back. At the moment the thread finishes it calls some methods on the old activity causing the activity to show a dialog. This causes the system to crash because the dialog tries to show itself with a reference to an activity that is not longer present on the screen. How can I achieve a dialog that is only shown if the activity is still active?

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• When to use try/catch

  - by coffeeaddict

  I'm always finding myself wanting to put a try/catch around the lets say Business Layer methods. But I feel though that I don't need a try/catch if I'm simply rethrowing it up to the Presentation Layer. Is that right? I should not be rethrowing an exception from code that's wrapped in a try/catch in a BL method and should be letting the caller which would be from the Presentation Layer code be using a try/catch to handle it there? The BL method will throw an error without the try/catch anyway..the compiler will. So it wouldn't make sense to use a try/catch in a BL method that's to be consumed by a layer higher up correct?

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• Advice Needed on Development of ConnectionWizard Custom Control

  - by SidC

  I have the need for an ASP.NET custom server control that will check the web.config file for a connectionstring name, prompt the user to create said connectionstring if not present, and execute create table stored procedures using the connection. This control will be embedded into a webpart for use in a WSS3.0 solution. Can anyone suggest some good tutorials on creating this type of control - specifically addressing use of connectionstrings? What methods/classes do I need to setup? Should I use the p&p data application block for this project? Thanks, Sid

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• How to stop an iteration of TextView when click in on one of the TextView?

  - by sgiro

  Hello, i have one doubt. I have an iteration of TextViews, and what i want is when i click in one TextView , i want stop the iteration and open a web, who can i know what TextView as been click on? i have this code: Iterator it = text.iterator(); while(it.hasNext()){ test = it.next(); test.setOnClickListener(new View.OnClickListener() { public void onClick(View v) { //mWebView = (WebView) findViewById(R.id.webview); mWebView.setWebViewClient(new WebViewClient() { @Override public boolean shouldOverrideUrlLoading(WebView view, String url) { view.loadUrl(url); return true; } }); mWebView.getSettings().setJavaScriptEnabled(true); mWebView.loadUrl(url); } }); // condition to stop the iteration when i click on TextView } And what i want is the condition to stop the iteration when i click on the TextView that i want see, i try using some methods that are in the TextView and don't work. Anyone can help me? Thanks and forgive my English

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