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  • Rails 2.3: How to create this SQL into a named_scope

    - by randombits
    Having a bit of difficulty figuring out how to create a named_scope from this SQL query: select * from foo where id NOT IN (select foo_id from bar) AND foo.category = ? ORDER BY RAND() LIMIT 1; Category should be variable to change. What's the most efficient way the named_scope can be written for the problem above?

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  • Is it possible to generate a .h macros file from bjam?

    - by Gnurou
    I need to dynamically generate some macros into a .h configuration file that C programs can include in order to check which options are enabled, in a fashion similar to what is possible with CMake's CONFIGURE_FILE macro. But after looking in the doc and the web, I could not find something useful. Is it possible to generate such a file from bjam and have the dependencies handled correctly? If so, how would you do it?

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  • Managing a user's PHP session with Cocoa Touch

    - by Calvin L
    I'm building an iPhone app, which will allow users to log in to a PHP web server that authenticates the user and starts a session. My idea for managing a session is to create a singleton User class that has a sharedLogin method. Would it be prudent to store the session variable in the shared instance in order to maintain the session?

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  • MySQL: What's the best to use, Unix TimeStamp Or DATETIME

    - by Axel
    Hello, Probably many coders want to ask this question. it is What's the adventages of each one of those MySQL time formats. and which one you will prefer to use it in your apps. For me i use Unix timestamp because maybe i find it easy to convert & order records with it, and also because i never tried the DATETIME thing. but anyways i'm ready to change my mind if anyone tells me i'm wrong. Thanks

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  • Ruby IpV6 Multicast Sending and Receive

    - by Francesco Vollero
    Hi, as object i'm tring to create a client and server scripts in order to send and receive multicast packages over IPv6. In IPv4 everything work as well, but i cannot figure out how to change it in IPv6. I start as basis from Multicasting In Ruby but seems ff02::1 isnt good for MULTICAST_ADDR. Thanks in advance.

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  • Implementing events to communicate between two processes - C

    - by Jamie Keeling
    Hello all! I have an application consisting of two windows, one communicates to the other and sends it a struct constaining two integers (In this case two rolls of a dice). I will be using events for the following circumstances: Process a sends data to process b, process b displays data Process a closes, in turn closing process b Process b closes a, in turn closing process a I have noticed that if the second process is constantly waiting for the first process to send data then the program will be just sat waiting, which is where the idea of implementing threads on each process occurred and I have started to implement this already. The problem i'm having is that I don't exactly have a lot of experience with threads and events so I'm not sure of the best way to actually implement what I want to do. Following is a small snippet of what I have so far in the producer application; Create thread: case IDM_FILE_ROLLDICE: { hDiceRoll = CreateThread( NULL, // lpThreadAttributes (default) 0, // dwStackSize (default) ThreadFunc(hMainWindow), // lpStartAddress NULL, // lpParameter 0, // dwCreationFlags &hDiceID // lpThreadId (returned by function) ); } break; The data being sent to the other process: DWORD WINAPI ThreadFunc(LPVOID passedHandle) { HANDLE hMainHandle = *((HANDLE*)passedHandle); WCHAR buffer[256]; LPCTSTR pBuf; LPVOID lpMsgBuf; LPVOID lpDisplayBuf; struct diceData storage; HANDLE hMapFile; DWORD dw; //Roll dice and store results in variable storage = RollDice(); hMapFile = CreateFileMapping( (HANDLE)0xFFFFFFFF, // use paging file NULL, // default security PAGE_READWRITE, // read/write access 0, // maximum object size (high-order DWORD) BUF_SIZE, // maximum object size (low-order DWORD) szName); // name of mapping object if (hMapFile == NULL) { dw = GetLastError(); MessageBox(hMainHandle,L"Could not create file mapping object",L"Error",MB_OK); return 1; } pBuf = (LPTSTR) MapViewOfFile(hMapFile, // handle to map object FILE_MAP_ALL_ACCESS, // read/write permission 0, 0, BUF_SIZE); if (pBuf == NULL) { MessageBox(hMainHandle,L"Could not map view of file",L"Error",MB_OK); CloseHandle(hMapFile); return 1; } CopyMemory((PVOID)pBuf, &storage, (_tcslen(szMsg) * sizeof(TCHAR))); //_getch(); MessageBox(hMainHandle,L"Completed!",L"Success",MB_OK); UnmapViewOfFile(pBuf); return 0; } I'm trying to find out how I would integrate an event with the threaded code to signify to the other process that something has happened, I've seen an MSDN article on using events but it's just confused me if anything, I'm coming up on empty whilst searching on the internet too. Thanks for any help Edit: I can only use the Create/Set/Open methods for events, sorry for not mentioning it earlier.

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  • SQL Server CTE referred in self joins slow

    - by Kharlos Dominguez
    Hello, I have written a table-valued UDF that starts by a CTE to return a subset of the rows from a large table. There are several joins in the CTE. A couple of inner and one left join to other tables, which don't contain a lot of rows. The CTE has a where clause that returns the rows within a date range, in order to return only the rows needed. I'm then referencing this CTE in 4 self left joins, in order to build subtotals using different criterias. The query is quite complex but here is a simplified pseudo-version of it WITH DataCTE as ( SELECT [columns] FROM table INNER JOIN table2 ON [...] INNER JOIN table3 ON [...] LEFT JOIN table3 ON [...] ) SELECT [aggregates_columns of each subset] FROM DataCTE Main LEFT JOIN DataCTE BananasSubset ON [...] AND Product = 'Bananas' AND Quality = 100 LEFT JOIN DataCTE DamagedBananasSubset ON [...] AND Product = 'Bananas' AND Quality < 20 LEFT JOIN DataCTE MangosSubset ON [...] GROUP BY [ I have the feeling that SQL Server gets confused and calls the CTE for each self join, which seems confirmed by looking at the execution plan, although I confess not being an expert at reading those. I would have assumed SQL Server to be smart enough to only perform the data retrieval from the CTE only once, rather than do it several times. I have tried the same approach but rather than using a CTE to get the subset of the data, I used the same select query as in the CTE, but made it output to a temp table instead. The version referring the CTE version takes 40 seconds. The version referring the temp table takes between 1 and 2 seconds. Why isn't SQL Server smart enough to keep the CTE results in memory? I like CTEs, especially in this case as my UDF is a table-valued one, so it allowed me to keep everything in a single statement. To use a temp table, I would need to write a multi-statement table valued UDF, which I find a slightly less elegant solution. Did some of you had this kind of performance issues with CTE, and if so, how did you get them sorted? Thanks, Kharlos

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  • count and fetch rows in php

    - by Mac Taylor
    hey guys i have a table in my mysql database named (names) now everyone can save their real names now i want to query this table and find out how many times these names used forexample the output should be : Jakob (20) Jenny (17) now this is my own code : list($usernames) =mysql_fetch_row(mysql_query('SELECT name FROM table_user GROUP BY name ORDER BY COUNT(name) DESC LIMIT 50 ')); list($c) =mysql_num_rows(mysql_query('SELECT COUNT(name) FROM table_user GROUP BY name ')); print $usernames.'('.$c.')' is this a correct approach ?!

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  • Grails exploded under tomcat

    - by xain
    Hi, is there a way to use Grails in "exploded" mode on tomcat in order to make individual changes in a running application (like a gif) without having to regenerate the entire war and upload it ? Something like adding an xml file in tomcat's conf/Catalina/localhost that points to an exploded grails application ? Thanks in advance.

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  • How can I use the HSL colorspace in Java?

    - by Eric
    I've had a look at the ColorSpace class, and found the constant TYPE_HLS (which presumably is just HSL in a different order). Can I use this constant to create a Color from hue, saturation, and luminosity? If not, are there any Java classes for this, or do I need to write my own?

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  • When Should One Call glGetError ?

    - by Ngu Soon Hui
    glLoadIdentity says GL_INVALID_OPERATION is generated if glLoadIdentity is executed between the execution of glBegin and the corresponding execution of glEnd. But GL_INVALID_OPERATION is a flag returns by glGetError. My question is, when should we call glGetError ( in order to know whether we are calling opengl in correct sequence)?

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  • stl priority queue based on lower value first

    - by russell
    I have a problem with stl priority queue.I want to have the priority queue in the increasing order,which is decreasing by default.Is there any way to do this in priority queue. And what is the complexity of building stl priority queue.If i use quick sort in an array which takes O(nlgn) is its complexity is similar to using priority queue??? Plz someone ans.Advanced thanx.

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  • How should Application.Run() be called for the main presenter a MVP WinForms app?

    - by Mr Roys
    I'm learning to apply MVP to a simple WinForms app (only one form) in C# and encountered an issue while creating the main presenter in static void Main(). Is it a good idea to expose a View from the Presenter in order to supply it as a parameter to Application.Run()? Currently, I've implemented an approach which allows me to not expose the View as a property of Presenter: static void Main() { IView view = new View(); Model model = new Model(); Presenter presenter = new Presenter(view, model); presenter.Start(); Application.Run(); } The Start and Stop methods in Presenter: public void Start() { view.Start(); } public void Stop() { view.Stop(); } The Start and Stop methods in View (a Windows Form): public void Start() { this.Show(); } public void Stop() { // only way to close a message loop called // via Application.Run(); without a Form parameter Application.Exit(); } The Application.Exit() call seems like an inelegant way to close the Form (and the application). The other alternative would be to expose the View as a public property of the Presenter in order to call Application.Run() with a Form parameter. static void Main() { IView view = new View(); Model model = new Model(); Presenter presenter = new Presenter(view, model); Application.Run(presenter.View); } The Start and Stop methods in Presenter remain the same. An additional property is added to return the View as a Form: public void Start() { view.Start(); } public void Stop() { view.Stop(); } // New property to return view as a Form for Application.Run(Form form); public System.Windows.Form View { get { return view as Form(); } } The Start and Stop methods in View (a Windows Form) would then be written as below: public void Start() { this.Show(); } public void Stop() { this.Close(); } Could anyone suggest which is the better approach and why? Or there even better ways to resolve this issue?

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  • MySQL Sub-query.. Doesn't provide proper information after 3 entries into table.

    - by Chris Keefer
    After I get 3 rows in my forum_threads table this no longer does it's job; to organize a list of active forum threads and put the most recently responded-to thread at the top of the list, followed by second most recent posted-to thread, followed by third, fourth, etc. Like I said, the query works wonders up until there is a fourth row added to forum_threads. SELECT forum_threads.*, forum_posts.thread_id FROM forum_threads INNER JOIN (SELECT MAX(id) AS id, thread_id as thread_id FROM forum_posts group by thread_id order by id DESC) forum_posts ON forum_threads.id = forum_posts.thread_id

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  • Java - Make an object collection friendly

    - by DutrowLLC
    If an object holds a unique primary key, what interfaces does it need to implement in order to be collection friendly especially in terms of being efficiently sortable, hashable, etc...? If the primary key is a string, how are these interfaces best implemented? Thanks!

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  • Create a nested list

    - by sico87
    How would I create a nested list, I currently have this public function getNav($cat,$subcat){ //gets all sub categories for a specific category if(!$this->checkValue($cat)) return false; //checks data $query = false; if($cat=='NULL'){ $sql = "SELECT itemID, title, parent, url, description, image FROM p_cat WHERE deleted = 0 AND parent is NULL ORDER BY position;"; $query = $this->db->query($sql) or die($this->db->error); }else{ //die($cat); $sql = "SET @parent = (SELECT c.itemID FROM p_cat c WHERE url = '".$this->sql($cat)."' AND deleted = 0); SELECT c1.itemID, c1.title, c1.parent, c1.url, c1.description, c1.image, (SELECT c2.url FROM p_cat c2 WHERE c2.itemID = c1.parent LIMIT 1) as parentUrl FROM p_cat c1 WHERE c1.deleted = 0 AND c1.parent = @parent ORDER BY c1.position;"; $query = $this->db->multi_query($sql) or die($this->db->error); $this->db->store_result(); $this->db->next_result(); $query = $this->db->store_result(); } return $query; } public function getNav($cat=false, $subcat=false){ //gets a list of all categories form this level, if $cat is false it returns top level nav if($cat==false || strtolower($cat)=='all-products') $cat='NULL'; $ds = $this->data->getNav($cat, $subcat); $nav = $ds ? $ds : false; $html = ''; //create html if($nav){ $html = '<ul>'; //var_dump($nav->fetch_assoc()); while($row = $nav->fetch_assoc()){ $url = isset($row['parentUrl']) ? $row['parentUrl'].'/'.$row['url'] : $row['url']; $current = $subcat==$row['url'] ? ' class="current"' : ''; $html .= '<li'.$current.'><a href="/'.$url.'/">'.$row['title'].'</a></li>'; } $html .='</ul>'; } return $html; } The sql returns parents and children, for each parent I need the child to nest in a list.

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  • How large is a "buffer" in PostgreSQL

    - by Konrad Garus
    I am using pg_buffercache module for finding hogs eating up my RAM cache. For example when I run this query: SELECT c.relname, count(*) AS buffers FROM pg_buffercache b INNER JOIN pg_class c ON b.relfilenode = c.relfilenode AND b.reldatabase IN (0, (SELECT oid FROM pg_database WHERE datname = current_database())) GROUP BY c.relname ORDER BY 2 DESC LIMIT 10; I discover that sample_table is using 120 buffers. How much is 120 buffers in bytes?

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