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  • Can anyone explain this strange behaviour?

    - by partizan
    Hi, guys. Here is the example with comments: class Program { // first version of structure public struct D1 { public double d; public int f; } // during some changes in code then we got D2 from D1 // Field f type became double while it was int before public struct D2 { public double d; public double f; } static void Main(string[] args) { // Scenario with the first version D1 a = new D1(); D1 b = new D1(); a.f = b.f = 1; a.d = 0.0; b.d = -0.0; bool r1 = a.Equals(b); // gives true, all is ok // The same scenario with the new one D2 c = new D2(); D2 d = new D2(); c.f = d.f = 1; c.d = 0.0; d.d = -0.0; bool r2 = c.Equals(d); // false! this is not the expected result } } So, what do you think about this?

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  • MySQL left outer join is slow

    - by Ryan Doherty
    Hi, hoping to get some help with this query, I've worked at it for a while now and can't get it any faster: SELECT date, count(id) as 'visits' FROM dates LEFT OUTER JOIN visits ON (dates.date = DATE(visits.start) and account_id = 40 ) WHERE date >= '2010-12-13' AND date <= '2011-1-13' GROUP BY date ORDER BY date ASC That query takes about 8 seconds to run. I've added indexes on dates.date, visits.start, visits.account_id and visits.start+visits.account_id and can't get it to run any faster. Table structure (only showing relevant columns in visit table): create table visits ( `id` int(11) NOT NULL AUTO_INCREMENT, `account_id` int(11) NOT NULL, `start` DATETIME NOT NULL, `end` DATETIME NULL, PRIMARY KEY (`id`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; CREATE TABLE `dates` ( `date` date NOT NULL, PRIMARY KEY (`date`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1; dates table contains all days from 2010-1-1 to 2020-1-1 (~3k rows). visits table contains about 400k rows dating from 2010-6-1 to yesterday. I'm using the date table so the join will return 0 visits for days there were no visits. Results I want for reference: +------------+--------+ | date | visits | +------------+--------+ | 2010-12-13 | 301 | | 2010-12-14 | 356 | | 2010-12-15 | 423 | | 2010-12-16 | 332 | | 2010-12-17 | 346 | | 2010-12-18 | 226 | | 2010-12-19 | 213 | | 2010-12-20 | 311 | | 2010-12-21 | 273 | | 2010-12-22 | 286 | | 2010-12-23 | 241 | | 2010-12-24 | 149 | | 2010-12-25 | 102 | | 2010-12-26 | 174 | | 2010-12-27 | 258 | | 2010-12-28 | 348 | | 2010-12-29 | 392 | | 2010-12-30 | 395 | | 2010-12-31 | 278 | | 2011-01-01 | 241 | | 2011-01-02 | 295 | | 2011-01-03 | 369 | | 2011-01-04 | 438 | | 2011-01-05 | 393 | | 2011-01-06 | 368 | | 2011-01-07 | 435 | | 2011-01-08 | 313 | | 2011-01-09 | 250 | | 2011-01-10 | 345 | | 2011-01-11 | 387 | | 2011-01-12 | 0 | | 2011-01-13 | 0 | +------------+--------+ Thanks in advance for any help!

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  • How should I link two items with MouseMovementListeners?

    - by user1708810
    I'm working on a program that will display two "views" of the same set of items. So I need to have something set up so that when the top down view is changed, the side view is updated (and vice versa). Here's a brief outline of the relevant code so you can get an idea of my structure so far: public class DraggableComponent extends JComponent { //Contains code for MouseMovementListener that makes the item draggable } public class ItemGraphic extends DraggableComponent { //Code to render the graphic } public class Item { private ItemGraphic topGraphic; private ItemGraphic sideGraphic; } I'm able to get each graphic to display fine in my GUI. I can also independently drag each graphic. I'm missing the "linking." Some ideas I've been thinking about: Have one listener for the whole GUI. Loop through each Item and if the cursor is within the bounds of either graphic, move the other graphic. I'm concerned about the efficiency of this method. Multiple "paired" listeners (not quite sure how this would work, but the idea is that each graphic would have a listener for the other paired graphic)

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  • How can I find the common ancestor of two nodes in a binary tree?

    - by Siddhant
    The Binary Tree here is not a Binary Search Tree. Its just a Binary Tree. The structure could be taken as - struct node { int data; struct node *left; struct node *right; }; The maximum solution I could work out with a friend was something of this sort - Consider this binary tree (from http://lcm.csa.iisc.ernet.in/dsa/node87.html) : The inorder traversal yields - 8, 4, 9, 2, 5, 1, 6, 3, 7 And the postorder traversal yields - 8, 9, 4, 5, 2, 6, 7, 3, 1 So for instance, if we want to find the common ancestor of nodes 8 and 5, then we make a list of all the nodes which are between 8 and 5 in the inorder tree traversal, which in this case happens to be [4, 9, 2]. Then we check which node in this list appears last in the postorder traversal, which is 2. Hence the common ancestor for 8 and 5 is 2. The complexity for this algorithm, I believe is O(n) (O(n) for inorder/postorder traversals, the rest of the steps again being O(n) since they are nothing more than simple iterations in arrays). But there is a strong chance that this is wrong. :-) But this is a very crude approach, and I'm not sure if it breaks down for some case. Is there any other (possibly more optimal) solution to this problem?

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  • Forming triangles from points and relations

    - by SiN
    Hello, I want to generate triangles from points and optional relations between them. Not all points form triangles, but many of them do. In the initial structure, I've got a database with the following tables: Nodes(id, value) Relations(id, nodeA, nodeB, value) Triangles(id, relation1_id, relation2_id, relation3_id) In order to generate triangles from both nodes and relations table, I've used the following query: INSERT INTO Triangles SELECT t1.id, t2.id , t3.id, FROM Relations t1, Relations t2, Relations t3 WHERE t1.id < t2.id AND t3.id > t1.id AND ( t1.nodeA = t2.nodeA AND (t3.nodeA = t1.nodeB AND t3.nodeB = t2.nodeB OR t3.nodeA = t2.nodeB AND t3.nodeB = t1.nodeB) OR t1.nodeA = t2.nodeB AND (t3.nodeA = t1.nodeB AND t3.nodeB = t2.nodeA OR t3.nodeA = t2.nodeA AND t3.nodeB = t1.nodeB) ) It's working perfectly on small sized data. (~< 50 points) In some cases however, I've got around 100 points all related to each other which leads to thousands of relations. So when the expected number of triangles is in the hundreds of thousands, or even in the millions, the query might take several hours. My main problem is not in the select query, while I see it execute in Management Studio, the returned results slow. I received around 2000 rows per minute, which is not acceptable for my case. As a matter of fact, the size of operations is being added up exponentionally and that is terribly affecting the performance. I've tried doing it as a LINQ to object from my code, but the performance was even worse. I've also tried using SqlBulkCopy on a reader from C# on the result, also with no luck. So the question is... Any ideas or workarounds?

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  • Void* array casting to float, int32, int16, etc.

    - by Griffin
    Hey guys, I've got an array of PCM data, it could be 16 bit, 24 bit packed, 32 bit, etc.. It could be signed, or unsigned, and it could be 32 or 64 bit floating point. It is currently stored as a "void**" matrix, indexed by channel, then by frame. The goal is to allow my library to take in any PCM format and buffer it, without requiring manipulation of the data to fit a designated structure. If the A/D converter spits out 24 bit packed arrays of interleaved PCM, I need to accept it gracefully. I also need to support 16 bit non interleaved, as well as any permutation of the above formats. I know the bit depth and other information at runtime, and I'm trying to code efficiently while not duplicating code. What I need is an effective way to cast the matrix, put PCM data into the matrix, and then pull it out later. I can cast the matrix to int32_t, or int16_t for the 32 and 16 bit signed PCM respectively, I'll probably have to store the 24 bit PCM in an int32_t for 32 bit, 8 bit byte systems as well. Can anyone recommend a good way to put data into this array, and pull it out later? I'd like to avoid large sections of code which look like: switch( mFormat ) { case 1: // unsigned 8 bit for( int i = 0; i < mChannels; i++ ) framesArray = (uint8_t*)pcm[i]; break; case 2: // signed 8 bit for( int i = 0; i < mChannels; i++ ) framesArray = (int8_t*)pcm[i]; break; case 3: // unsigned 16 bit ... Limitations: I'm working in C/C++, no templates, no RTTI, no STL. Think embedded. Things get trickier when I have to port this to a DSP with 16 bit bytes. Does anybody have any useful macros they might be willing to share? Thanks, -Griff

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  • Parameter meaning of CBasePin::GetMediaType(int iPosition, ...) method

    - by user325320
    Thanks to everyone who views my question. http://msdn.microsoft.com/en-us/library/windows/desktop/dd368709(v=vs.85).aspx It is not very clear from the documentation regarding the iPosition parameter for virtual HRESULT GetMediaType( int iPosition, CMediaType *pMediaType ); It is said "Zero-based index value.", but what kind of index it is? the index of the samples? I have a source filter sending the H.264 NALU flows (MEDIASUBTYPE_AVC1) and it works very well except that the SPS/PPS may be changed after the video is played for a while. The SPS and PPS are appended to the MPEG2VIDEOINFO structure, which is passed in CMediaType::SetFormat method when GetMediaType method is called. and there is another version of GetMediaType which accepts the iPosition parameter. It seems I can use this method to update the SPS / PPS. My question is: What does the iPosition param mean, and how does Decoder Filter know which SPS/PPS are assigned for each NALU sample. HRESULT GetMediaType(int iPosition, CMediaType *pMediaType) { ATLTRACE( "\nGetMediaType( iPosition = %d ) ", iPosition); CheckPointer(pMediaType,E_POINTER); CAutoLock lock(m_pFilter->pStateLock()); if (iPosition < 0) { return E_INVALIDARG; } if (iPosition == 0) { pMediaType->InitMediaType(); pMediaType->SetType(&MEDIATYPE_Video); pMediaType->SetFormatType(&FORMAT_MPEG2Video); pMediaType->SetSubtype(&MEDIASUBTYPE_AVC1); pMediaType->SetVariableSize(); } int nCurrentSampleID; DWORD dwSize = m_pFlvFile->GetVideoFormatBufferSize(nCurrentSampleID); LPBYTE pBuffer = pMediaType->ReallocFormatBuffer(dwSize); memcpy( pBuffer, m_pFlvFile->GetVideoFormatBuffer(nCurrentSampleID), dwSize); pMediaType->SetFormat(pBuffer, dwSize); return S_OK; }

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  • Sql Server 2005 Database Tables - Row Comparison Column By Column.

    - by Goober
    Scenario I have an TWO datbase tables of exactly the SAME STRUCTURE. The difference between these tables is that one contains data populated by one application and the other is populated by a different application. Each application is trying to produce the same result, but using two different methods of implementation. Proposed Idea What I want to do, is run both applications, which will roughly produce 35000 rows containing 10 columns each - So all in all, 70000 rows of data, I then want to compare each row of data, COLUMN BY COLUMN to check whether the values are the same or not. Current Thoughts Since there is so much data to compare, I feel that the best way in which to do this would be to write an application, preferably in C# (but if necessary, T-sql), to compare each row of data column by column, and write out any failed comparisons to a text log file. Question Could anybody suggest an efficient way in which to perform column by column row comparison for 70000 rows worth of data? I'm struggling for ideas on how to tackle this problem. Extra Detail The two applications are both written in C# .Net 3.5. The Database is running on Sql Server 2005. Help greatly appreciated.

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  • NHibernate / multiple sessions and nested objects

    - by bernhardrusch
    We are using NHibernate in a rich client application. It is a pretty open application (the user searches for a dataset or creates a new one, changes the data and saves the data set. We leave the session open, because sometimes we have to lazy load some properties of the object (nested object structure). This means one big problem if we leave the session open, the db (MySQL) closes the connection and we are not able to find this out and it throws an exception (socket communication error) when accessing the database (we are thinking about testing the db connection before accessing the object - but this is not really optimal neither, the other option would be to set back the timeout of the db connection , but this just doesn't seem to well). So - is it possible to reconnect the session to a new database connection ? Another problem is it possible to get an object from one session and then re-attach it to another session ? (I often hear that session.lock should work for this - but this doesn't work so well in our application - so I ended up getting a "fresh" object from the session and copy the data over manually - which is a little bit cumbersome) Any ideas for this ?

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  • Missing tables on Scaffold Dynamic Data page

    - by Ben Amada
    I created a Linq-to-SQL DBML for the first time. I dragged and dropped all my tables over to the designer. The tables all appear in the designer.cs file. In Global.asax, I also have model.RegisterContext() with the ScaffoldAllTables = true option. The routes are also setup. I can pull up the Scaffolding page, but there's at least one table that is missing that I'm trying to get to show up. This missing table has a relationship with a child table that references it. The child table appears. When viewing data for the child table, the column that references the missing/parent table shows the numeric PK int value, rather than showing the "name". So instead of showing "Cars" it shows 1, and instead of showing "Planes" it shows 2, etc. There's another table in the DB that has the same type of structure as the missing table, and it is correctly appearing in the scaffolded tables. For this missing table, I've tried explicitly adding the ScaffoldTable attribute to no avail. Does anyone know what would cause a table like this to not appear in the list Scaffolded tables? Thanks very much.

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  • Codeigniter .htaccess not working in subdirectory

    - by xzdead
    I have this codeingniter project structure webRoot | |/application | | | |/controllers | | | |/admin | |/public | | | |/admin | | | | | |/css | | |/img | |/css | |/img And this is my .htacess file, located in /public. I use this in every local project running xampp: <IfModule mod_rewrite.c> RewriteEngine On RewriteBase / RewriteCond %{REQUEST_FILENAME} !-f RewriteRule ^(.*)$ index.php/$1 [L] </IfModule> <IfModule !mod_rewrite.c> # If we don't have mod_rewrite installed, all 404's # can be sent to index.php, and everything works as normal. # Submitted by: ElliotHaughin ErrorDocument 404 /index.php </IfModule> It works fine in localhost, but doesn't work in a dreamhost server. I always get "no input file specified". So after searching the web and trying lots of combinations, the best I got is this .htaccess file: Options +FollowSymLinks RewriteEngine On RewriteCond %{REQUEST_FILENAME} !-d RewriteCond %{REQUEST_FILENAME} !-f RewriteRule ^ index.php [L] With this one, if I go to http://development.mydomain.com - I see the codeigniter welcome page But if I go to: http://development.mydomain.com/admin - I see the directory listing of /public/admin and doesn't execute the controller in /application/controllers/admin Again, if I go to: http://development.mydomain.com/admin/admin - I see the private area, it executes the controller and goes to the default controller defined in routes, "dashboard" This works fine too: http://development.mydomain.com/admin/dashboard I have set in my config file: $config['index_page'] = ''; $config['base_url'] = ''; $config['uri_protocol'] = 'AUTO'; I think that whatever is wrong in my .htaccess is causing other path issues I have with my project. Any help would be great. Thanks to all in advance EDIT: I removed this line: RewriteCond %{REQUEST_FILENAME} !-d because admin directory exists, that's why I see the public directory listing. But now I see the codeigniter welcome page when I go to http://development.mydomain.com/admin So now my .htaccess file looks like: Options +FollowSymLinks RewriteEngine On RewriteCond %{REQUEST_FILENAME} !-f RewriteRule ^ index.php [L] #RewriteRule ^(.*)$ /index.php?/$1 [L] I also tried with the commented RewriteRule but I get the same result.

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  • How should I handle header files in a bundle?

    - by ldiqual
    I want to develop a program that relies on plugins (here: loadable bundles) to work. Multiple plugins are asked to use the same AFNetworking ressource to make network requests. However, I don't know where to put AFNetworking and CustomPluginProtocol headers. Here is how my program structure looks like for now: MyApp.xcodeproj - AFNetworking - Header.h - Plugins - Plugin1.xcodeproj - PrincipalClass.m - Plugin2.xcodeproj - PrincipalClass.m - Classes - CustomPluginProtocol.h - MainClass.m Of course, every principalClass from PluginN complies to the CustomPluginProtocol. Do the headers have to be copied in each bundle ? Can I just include the main program AFNetworking headers from my plugins ? If so (and that's what I do for now), I don't have any completion. How can I get it ? Edit Ok, so maybe I wasn't clear in my question. I want my plugins to use sources from the main application, let's say CommonClass.m and CommonClass.h. Do the plugins need CommonClass.h in their bundle, and if not, how do I enable completion when I'm in the plugin scope ?

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  • Creating Modules for VB Program (Similar to firefox add on)

    - by Assimilater
    Hi all. I have a contact manager program that I'd like to design for multiple network marketing companies. My desired structure would include a core program which covers basic contact management functions. After that one could purchase a module for their specific network marketing company. This module would contain a variety of controls that the original program would need to be able to manipulate. Here is an example of what it would have to have: A group box containing buttons that link to a genealogy view, and the option to import one's donwnline from the back office provided by a company. A panel which is displayed on the contact page allowing the user to input business information or which will be filled by importing a downline from the back office: ie business ID, qualification level, sponsor information etc. a panel displayed when one searches for contacts on the contact list page which allows the user to sort based on information such as when they joined, what their business id is and so forth. a panel which is displayed in a personal business overview page which presents to an individual how many people in their downline are at each qualification level and develop a mailing list for individuals of a certain qualification level. I have the code developed to perform all these functions, I just wanted to give you an example of what needed to be done. I'm thinking that what I'm trying to create is a library that one can download and the program will recognize, but I'm not really sure where to go. What I'm really trying to do is figure out what kind of file I can make that will contain all this code and the GUI information that the program will recognize. Any ideas? With thanks, John

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  • Rails: RESTful Find, Initialize, or Create

    - by Andrew
    I have an app that has Cities in it. I'm looking for some suggestions on how to RESTfully structure a controller so that I can lookup, initialize, and create city records via AJAX requests. For instance: Given a text field city_name A user enters the name of a City, like "Paris, France" The app checks this location to see if there is such a city in the database already If there is, it returns the city object If there is not, it returns a new record initialized with the name "Paris" and the country "France", and prompts the user to confirm they want to add this city to the database If the user says "Yes" the record is saved. If not the record is discarded and the form is cleared. Now, my first approach was to change the Create action to use find_or_create, so that an AJAX post to cities_path would result in either returning the existing city or creating it and returning it. That works ok... However, it would be better to setup controller actions that would take a string input, find , or else initialize and return, then only create if the user confirms the generated record is correct. The ideal scenario would put this all in one action so AJAX request can go to that url, the server responds with JSON objects, and javascript can handle things from there. I'd like to keep all the user-interaction logic client side, and also minimize the number of requests it takes to achieve this. Any suggestions on the cleanest, most RESTful way to accomplish this?

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  • Entity Framework one-to-one relationship mapping flattened in code

    - by Josh Close
    I have a table structure like so. Address: AddressId int not null primary key identity ...more columns AddressContinental: AddressId int not null primary key identity foreign key to pk of Address County State AddressInternational: AddressId int not null primary key identity foreign key to pk of Address ProvinceRegion I don't have control over schema, this is just the way it is. Now, what I want to do is have a single Address object. public class Address { public int AddressId { get; set; } public County County { get; set; } public State State { get; set } public ProvinceRegion { get; set; } } I want to have EF pull it out of the database as a single entity. When saving, I want to save the single entity and have EF know to split it into the three tables. How would I map this in EF 4.1 Code First? I've been searching around and haven't found anything that meets my case yet. UPDATE An address record will have a record in Address and one in either AddressContinental or AddressInternational, but not both.

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  • MySQL query problem

    - by Luke
    Ok, I have the following problem. I have two InnoDB tables: 'places' and 'events'. One place can have many events, but event can be created without entering place. In this case event's foreign key is NULL. Simplified structure of the tables looks as follows: CREATE TABLE IF NOT EXISTS `events` ( `id` int(11) unsigned NOT NULL AUTO_INCREMENT, `name` varchar(255) COLLATE utf8_bin NOT NULL, `places_id` int(9) unsigned DEFAULT NULL, PRIMARY KEY (`id`), KEY `fk_events_places` (`places_id`), ) ENGINE=InnoDB; ALTER TABLE `events` ADD CONSTRAINT `events_ibfk_1` FOREIGN KEY (`places_id`) REFERENCES `places` (`id`) ON DELETE CASCADE ON UPDATE NO ACTION; CREATE TABLE IF NOT EXISTS `places` ( `id` int(9) unsigned NOT NULL AUTO_INCREMENT, `name` varchar(255) COLLATE utf8_bin NOT NULL, PRIMARY KEY (`id`), ) ENGINE=InnoDB; Question is, how to construct query which contains name of the event and name of the corresponding place (or no value, in case there is no place assigned?). I am able to do it with two queries, but then I am visibly separating events which have place assigned from the ones that are without place. Help really appreciated.

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  • Using variables before include()ing them

    - by phenry
    I'm using a file, page.php, as an HTML container for several content files; i.e., page.php defines most of the common structure of the page, and the content files just contain the text that's unique to every page. What I would like to do is include some PHP code with each content file that defines metadata for the page such as its title, a banner graphic to use, etc. For example, a content file might look like this (simplified): <?php $page_title="My Title"; ?> <h1>Hello world!</h1> The name of the file would be passed as a URL parameter to page.php, which would look like this: <html> <head> <title><?php echo $page_title; ?></title> </head> <body> <?php include($_GET['page']); ?> </body> </html> The problem with this approach is that the variable gets defined after it is used, which of course won't work. Output buffering also doesn't seem to help. Is there an alternate approach I can use? I'd prefer not to define the text in the content file as a PHP heredoc block, because that smashes the HTML syntax highlighting in my text editor. I also don't want to use JavaScript to rewrite page elements after the fact, because many of these pages don't otherwise use JavaScript and I'd rather not introduce it as a dependency if I don't have to.

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  • Mysql count and sum from two diferent tables

    - by Agent_x
    Hi all, i have a problem with some querys in php and mysql: I have 2 diferent tables with one field in common: table 1 id | hits | num_g | cats | usr_id |active 1 | 10 | 11 | 1 | 53 | 1 2 | 13 | 16 | 3 | 53 | 1 1 | 10 | 22 | 1 | 22 | 1 1 | 10 | 21 | 3 | 22 | 1 1 | 2 | 6 | 2 | 11 | 1 1 | 11 | 1 | 1 | 11 | 1 table 2 id | usr_id | points 1 | 53 | 300 Now i use this statement to sum just the total from the table 1 every id count + 1 too SELECT usr_id, COUNT( id ) + SUM( num_g + hits ) AS tot_h FROM table1 WHERE usr_id!='0' GROUP BY usr_id ASC LIMIT 0 , 15 and i get the total for each usr_id usr_id| tot_h | 53 | 50 22 | 63 11 | 20 until here all is ok, now i have a second table with extra points (table2) I try this: SELECT usr_id, COUNT( id ) + SUM( num_g + hits ) + (SELECT points FROM table2 WHERE usr_id != '0' ) AS tot_h FROM table1 WHERE usr_id != '0' GROUP BY usr_id ASC LIMIT 0 , 15 but it seems to sum the 300 extra points to all users: usr_id| tot_h | 53 | 350 22 | 363 11 | 320 Now how i can get the total like the first try but + the secon table in one statement? because now i have just one entry in the second table but i can be more there. thanks for all the help. =============================================================================== hi thomas thanks for your reply, i think is in the right direction, but im getting weirds results, like usr_id | tot_h 22 | NULL <== i think the null its because that usr_id as no value in the table2 53 | 1033 Its like the second user is getting all the the values. then i try this one: SELECT table1.usr_id, COUNT( table1.id ) + SUM( table1.num_g + table1.hits + table2.points ) AS tot_h FROM table1 LEFT JOIN table2 ON table2.usr_id = table1.usr_id WHERE table1.usr_id != '0' AND table2.usr_id = table1.usr_id GROUP BY table1.usr_id ASC Same result i just get the sum of all values and not by each user, i need something like this result: usr_id | tot_h 53 | 53 <==== plus 300 points on table1 22 | 56 <==== plus 100 points on table2 /////////the result i need //////////// usr_id | tot_h 53 | 353 <==== plus 300 points on table2 22 | 156 <==== plus 100 points on table2 I think the structure need to be something like this Pseudo statements ;) from table1 count all id to get the number of record where the usr_id are then sum hits + num_g and from table2 select the extra points where the usr_id are the same as table1 and get teh result: usr_id | tot_h 53 | 353 22 | 156

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  • Debugging instance of another thread altering my data

    - by Mick
    I have a huge global array of structures. Some regions of the array are tied to individual threads and those threads can modify their regions of the array without having to use critical sections. But there is one special region of the array which all threads may have access to. The code that accesses these parts of the array needs to carefully use critical sections (each array element has its own critical section) to prevent any possibility of two threads writing to the structure simultaneously. Now I have a mysterious bug I am trying to chase, it is occurring unpredictably and very infrequently. It seems that one of the structures is being filled with some incorrect number. One obvious explanation is that another thread has accidentally been allowed to set this number when it should be excluded from doing so. Unfortunately it seems close to impossible to track this bug. The array element in which the bad data appears is different each time. What I would love to be able to do is set some kind of trap for the bug as follows: I would enter a critical section for array element N, then I know that no other thread should be able to touch the data, then (until I exit the critical section) set some kind of flag to a debugging tool saying "if any other thread attempts to change the data here please break and show me the offending patch of source code"... but I suspect no such tool exists... or does it? Or is there some completely different debugging methodology that I should be employing.

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  • Write file need to optimised for heavy traffic part 2

    - by Clayton Leung
    For anyone interest to see where I come from you can refer to part 1, but it is not necessary. write file need to optimised for heavy traffic Below is a snippet of code I have written to capture some financial tick data from the broker API. The code will run without error. I need to optimize the code, because in peak hours the zf_TickEvent method will be call more than 10000 times a second. I use a memorystream to hold the data until it reaches a certain size, then I output it into a text file. The broker API is only single threaded. void zf_TickEvent(object sender, ZenFire.TickEventArgs e) { outputString = string.Format("{0},{1},{2},{3},{4}\r\n", e.TimeStamp.ToString(timeFmt), e.Product.ToString(), Enum.GetName(typeof(ZenFire.TickType), e.Type), e.Price, e.Volume); fillBuffer(outputString); } public class memoryStreamClass { public static MemoryStream ms = new MemoryStream(); } void fillBuffer(string outputString) { byte[] outputByte = Encoding.ASCII.GetBytes(outputString); memoryStreamClass.ms.Write(outputByte, 0, outputByte.Length); if (memoryStreamClass.ms.Length > 8192) { emptyBuffer(memoryStreamClass.ms); memoryStreamClass.ms.SetLength(0); memoryStreamClass.ms.Position = 0; } } void emptyBuffer(MemoryStream ms) { FileStream outStream = new FileStream("c:\\test.txt", FileMode.Append); ms.WriteTo(outStream); outStream.Flush(); outStream.Close(); } Question: Any suggestion to make this even faster? I will try to vary the buffer length but in terms of code structure, is this (almost) the fastest? When memorystream is filled up and I am emptying it to the file, what would happen to the new data coming in? Do I need to implement a second buffer to hold that data while I am emptying my first buffer? Or is c# smart enough to figure it out? Thanks for any advice

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  • Does jQuery have an equivalent to Prototype's Element.identify?

    - by Alan Storm
    Is there a built in method or defacto default plugin that will let you automatically assign an unique ID to an element in jQuery, or do you need to implement something like this yourself? I'm looking for the jQuery equivalent to Prototype's identify method Here's an example. I have some HTML structure on a page that looks like this <span id="prefix_1">foo bar</span> ... <div id="foo"> <span></span> <span></span> <span></span> </div> I want to assign each of the spans an ID that will be unique to the page. So after calling something like this $('#foo span').identify('prefix'); //fake code, no such method The rendered DOM would look something like this <span id="prefix_1">foo bar</span> ... <div id="foo"> <span id="prefix_2"></span> <span id="prefix_3"></span> <span id="prefix_4"></span> </div> Is there anything official-ish/robust for jQuery, or is this something most jQuery developers roll on their own?

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  • Nested <ul><li> navigation menu using a recursive Python function

    - by Alex
    Hi. I want to render this data structure as an unordered list. menu = [ [1, 0], [2, 1], [3, 1], [4, 3], [5, 3], [6, 5], [7,1] ] [n][0] is the key [n][1] references the parent key The desired output is: <ul> <li>Node 1</li> <ul> <li>Node 2</li> <li>Node 3</li> <ul> <li>Node 4</li> <li>Node 5</li> <ul> <li>Node 6</li> </ul> </ul> <li>Node 7</li> </ul> </ul> I could probably do this without recursion but that would be no fun. Unfortunately, I am having problems putting it all together. I don't have much experience with recursion and this is proving to be very difficult for me to build and debug. What is the most efficient way to solve this problem in Python? Thanks!

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  • Where are possible locations of queueing/buffering delays in Linux multicast?

    - by Matt
    We make heavy use of multicasting messaging across many Linux servers on a LAN. We are seeing a lot of delays. We basically send an enormous number of small packages. We are more concerned with latency than throughput. The machines are all modern, multi-core (at least four, generally eight, 16 if you count hyperthreading) machines, always with a load of 2.0 or less, usually with a load less than 1.0. The networking hardware is also under 50% capacity. The delays we see look like queueing delays: the packets will quickly start increasing in latency, until it looks like they jam up, then return back to normal. The messaging structure is basically this: in the "sending thread", pull messages from a queue, add a timestamp (using gettimeofday()), then call send(). The receiving program receives the message, timestamps the receive time, and pushes it in a queue. In a separate thread, the queue is processed, analyzing the difference between sending and receiving timestamps. (Note that our internal queues are not part of the problem, since the timestamps are added outside of our internal queuing.) We don't really know where to start looking for an answer to this problem. We're not familiar with Linux internals. Our suspicion is that the kernel is queuing or buffering the packets, either on the send side or the receive side (or both). But we don't know how to track this down and trace it. For what it's worth, we're using CentOS 4.x (RHEL kernel 2.6.9).

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  • Behavior of Struts2 and convention-plugin when there is Index(extends ActionSupport)

    - by hanishi
    We have an Action class named 'Index' immediately under com.example.common.action and is annotated @ParentPackage('default') which is declared in package directive in struts.xml and has "/" for its namespace and extends "struts-default". It also declares @Result so that it responses with jsp files corresponding the string values returned by its execute() method. In our struts.xml, the following struts setting is configured along with other necessary configurations that are needed for convention-plugin. <constant name="struts.action.extension" value=","/> When accessing /my_context/none_existing_path, the request apparently hits this Index class and the contents of the jsp declared in the Index's @Result section gets returned. However, if we provide /my_context/, we receive the following error: HTTP Status 404-There is no Action mapped for namespace[/] and action name [] associated with context path [/my_context]. We want to know the reason why accessing /my_context/none_existing_path, where none_existing_path has no matching action, can fallback to Index class, but error is returned when when the URL requested is just /my_context/. Currently, our convention-plugin settings are declared as follows: <constant name="struts.convention.package.locators.basePackage" value="com.example"/> <constant name="struts.convention.package.locators" value="action"/> Strangely, if we changed the value of the struts.convention.package.locators.basePackage to om.example.common, in which the aforementioned Index file can be immediately found by narrowing the search scope, requesting /my_context/ displays the content of the jsps declared in @Result section of the Index class. However, as our action classes are distributed throughout the com.example.[a-z].action packages, where [a-z] represents the large volume of directories we have in our package structure, we cannot use this trick as a workaround. We have also tried placing index.jsp at the top level of the class path, and have the index.jsp redirect to /my_context/index, which worked but not what we want. Could this be a bug? We appreciate your responses. Thank you in advance. EDIT: JIRA registered, problem solved (from Struts 2.3.12 up)

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  • Attempting to calculate width of Map Overlays on the fly

    - by Bloudermilk
    Hey all- I am working on an Android app that utilizes the Google Maps API MapView, MapController, MapActivity, and ItemizedOverlay. I am basically trying to recreate certain functionalities of the Maps app (damn Google for not providing speech bubbles—for lack of a better name—for items!), particularly those speech bubbles. I have an invisible XML structure for the speech bubble in the XML layout file containing my MapView. The first time I show a speech bubble I grab that XML and remove it from it's current parent, applying some ItemizedOverlay.LayoutParams to it, and add it to the MapView as an Overlay. I position it above the item that was selected, fill it with the proper text, then set it to visible. This all works great. The goal here, though, is to also automatically animate the map to reveal any parts of a speech bubble that may be off-screen when it opens. So I'm trying popup.getWidth() (popup is the instance of my LinearLayout that is the speech bubble) after I do all the manipulation to the bubble, even after I display it to the user. Problem is, popup.getWidth() is returning me the width of the previously displayed popup, not the currently displayed one. I can't figure out why this would be happening if I'm fetching the width after I set it to visible with its new dimensions (which, by the way, are relative when I'm setting them with LayoutParams: fill_content for both width and height).. I have even tried forcing both the MapView and the "popup" to invalidate() before trying to fetch the width. Any ideas why this may be happening? How can I force the View to settle into its new dimensions before trying to fetch them? Thanks! Nick

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