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  • help me with the following sql query

    - by rupeshmalviya
    could somebody correct my following query, i am novice to software development realm, i am to a string builder object in comma separated form to my query but it's not producing desired result qyery is as follows and string cmd = "SELECT * FROM [placed_student] WHERE passout_year=@passout AND company_id=@companyId AND course_id=@courseId AND branch_id IN('" + sb + "')"; StringBuilder sb = new StringBuilder(); foreach (ListItem li in branch.Items) { if (li.Selected == true) { sb.Append(Convert.ToInt32(li.Value) +", "); } } li is integer value of my check box list which are getting generated may be differne at different time ...please also suggest me some good source to learn sql..

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  • How to make my WPF application as FAST as Outlook

    - by Raul Otaño
    The commons WPF applications take some time for loading medium complex views, once the view is loaded it works fine. For example in a Master - Detail view, if the Detail view is very complex and use different DataTemplates take some seconds (2-3 seconds) for load the view. When i open the Outlook application, for instance, it renders complex views and it is relative much more fast. Is there a way for increase the performance of my WPF application? Maybe a way for not loading the template's data every time that change the "master" item, and load it only one time in the app time live? i will appreciate any suggestion.

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  • get foreign key objects in a single query - Django

    - by John
    Hi I have 2 models in my django code: class ModelA(models.Model): name = models.CharField(max_length=255) description = models.CharField(max_length=255) created_by = models.ForeignKey(User) class ModelB(models.Model): category = models.CharField(max_length=255) modela_link = models.ForeignKey(ModelA, 'modelb_link') functions = models.CharField(max_length=255) created_by = models.ForeignKey(User) Say ModelA has 100 records, all of which may or may not have links to ModelB Now say I want to get a list of every ModelA record along with the data from ModelB I would do: list_a = ModelA.objects.all() Then to get the data for ModelB I would have to do for i in list_a: i.additional_data = i.modelb_link.all() However this runs a query on every instance of i. Thus making 101 queries to run. Is there any way of running this all in just 1 query. Or at least less than the 101 queries. I've tried putting in ModelA.objects.select_related().all() but this didn't seem to have any effect. Thanks

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  • Making linq avoid using in memory filtering where possible

    - by linqmonkey
    Consider the these two LINQ2SQL data retrieval methods. The first creates a 'proper' SQL statement that filters the data, but requires passing the data context into the method. The second has a nicer syntax but loads the entire list of that accounts projects, then does in memory filtering. Is there any way to preserve the syntax of the second method but with the performance advantage of the first? public partial class Account { public IQueryable<Project> GetProjectsByYear(LinqDataContext context, int year) { return context.Projects.Where(p => p.AccountID==this.AccountID && p.Year==year).OrderBy(p => p.ProjectNo) } public IQueryable<Project> GetProjectsByYear(int year) { return this.Projects.Where(p => p.Year==year).OrderBy(p => p.ProjectNo).AsQueryable() } }

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  • Does a servlet-based stack have significant overheads?

    - by John
    I don't know if it's simply because page-loads take a little time, or the way servlets have an abstraction framework above the 'bare metal' of HTTP, or just because of the "Enterprise" in Jave-EE, but in my head I have the notion that a servlet-based app is inherently adding overhead compared to a Java app which simply deals with sockets directly. Forget web-pages, imagine instead a Java server app where you send it a question over an HTTP request and it looks up an answer from memory and returns the answer in the response. You can easily write a Java socket-based app which does this, you can also do a servlet approach and get away from the "bare metal" of sockets. Is there any measurable performance impact to be expected implementing the same approach using Servlets rather than a custom socket-based HTTP listening app? And yes, I am hazy on the exact data sent in HTTP requests and I know it's a vague question. It's really about whether servlet implementations have lots of layers of indirection or anything else that would add up to a significant overhead per call, where by significant I mean maybe an additional 0.1s or more.

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  • Minimizing calls to database in rails

    - by ming yeow
    Hi guys, i am familiar with memcached and eager loading, but neither seems to solve the problem i am facing. My main performance lag comes from hundreds of data retrieval calls from the database. The tricky thing is that I do not know which set of users i need to retrieve until i have several steps of computation. I can refactor my code, but i was wondering how you experts handle this situation? I think it should be a fairly common situation def newsfeed - find out which users i need - retrieve those users via DB - find out which events happened for these users - for each of those events - retrieve new set of users - find out which groups are relevant - for each of those groups - retrieve new set of users - etc, etc end

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  • PHP 5.3 Namespaces should i use every PHP function with backslash?

    - by lhwparis
    Hi, im now using namespaces in PHP 5.3 now there is a fallback mechanism for functions which dont exist in the namespace. so php every time checks if the function exists in namespace and then tries to load it from global space. So what about all php internal functions? strstr for example? Should i now use every php internal function with a \ ? to avoid php first checking the namespace? is this fallback a huge performance drop? what do you think?

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  • how to convert legacy query to ActiveRecord Rails way

    - by josh
    I have a query in my code as below @sqladdpayment = "INSERT INTO payments (orderid, ttlprodcost, paytype, paystatus,created_at,updated_at,userid,storeid) VALUES ('" + session[:ordersid] + "', '" + session[:totalcost] + "', '" + "1"+ "', '" + "complete" +"',current_date, current_date, '"+"1"+"','"+ "1"+"')" Here the table payments and primary key is orderid. Now, I know if I convert this to the ActiveRecord way then I will not have to put update_date, current_date because it will put that on it's own. It will also put orderid on it's own also (auto_increment). I am looking for a way to convert the above query to ActiveRecord Rails way but still be able to put orderid on my own (session[:ordersid]). I do not want to rely on auto_increment because then I will have to refactor lot of the other code. This might be a quick and dirty fix but I want to know whether this type of flexibility is offered in rails? I have wondered about this question many times. Why won't rails allow me to have that flexibility?

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  • Split query result by half in TSQL (obtain 2 resultsets/tables)

    - by rubdottocom
    I have a query that returns a large number of heavy rows. When I transform this rows in a list of CustomObject I have a big memory peak, and this transformation is made by a custom dotnet framework that I can't modify. I need to retrieve a less number of rows to do "the transform" in two passes and then avoid the momery peak. How can I split the result of a query by half? I need to do it in DB layer. I thing to do a "Top count(*)/2" but how to get the other half? Thank you!

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  • If statement in MySQL query with PHP

    - by user1104854
    Is it possible to use an if statement in a MySQL query in a similar what I'm showing? I want to grab some information for upcoming events(not ones with previous dates). ini_set('date.timezone', 'America/New_York'); $timestamp = date('m/d/Y'); $sql = "select eventID,eventTitle,eventDate from events where eventLocationID = $locationID ORDER BY eventDate DESC IF(eventDate > $timestamp) "; I really want to avoid doing post-query if statements that will only print if it's after today's date because I run it through a pagination function, and I'd really prefer to avoid tinkering with that.

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  • Best way to access nested data structures?

    - by Blackshark
    I would like to know what the best way (performance wise) to access a large data structure is. There are about hundred ways to do it but what is the most accessible for the compiler to optimize? One can access a value by foo[someindex].bar[indexlist[i].subelement[j]].baz[0] or create some pointer aliases like sometype_t* tmpfoo = &foo[someindex]; tmpfoo->bar[indexlist[i].subelement[j]].baz[0] or create reference aliases like sometype_t &tmpfoo = foo[someindex]; tmpfoo.bar[indexlist[i].subelement[j]].baz[0] and so forth...

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  • update query not working in array

    - by Suresh PHP Begginer
    here my code: i want to update the field by array. i just fetch the data's from table then i want to update the the field for same table // select query to get the value for($j=0;$j<count($capacity);$j++) { $capaci=$capacity[$j]; // select query to get the value $sql2=mysql_query("SELECT recieved-allocate*plate_quantity as ans from total_values where capacity='$capaci'"); while($fetch=mysql_fetch_array($sql2)) { $recieves=$fetch['ans']; $sql3="update total_values set recieved='$recieves' where capacity='$capaci' and month='$mon'"; mysql_query($sql3); } }

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  • Filter Phrase Query

    - by alsuelo
    I try to filter a phrase to make a search in my website i've this query, this code working with one word but when i type wit more than one isn't working becuase the print is without spaces. $phrase = $this->getState($this->context.".filter_phrase"); printf("Original string: %s\n", $phrase); if(!empty($phrase)) { $escaped = $db->escape($phrase, true); printf("Escaped string: %s\n", $escaped); $quoted = $db->quote("%" . $escaped . "%" , false); $query->where ('a.title LIKE ' .$quoted); } Example i type king and the output is king , when i type the king the output is theking, i want to know if exist any way to conserve the blank spaces.

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  • Interpreted languages: The higher-level the faster?

    - by immersion
    I have designed around 5 experimental languages and interpreters for them so far, for education, as a hobby and for fun. One thing I noticed: The assembly-like language featuring only subroutines and conditional jumps as structures was much slower than the high-level language featuring if, while and so on. I developed them both simultaneously and both were interpreted languages. I wrote the interpreters in C++ and I tried to optimize the code-execution part to be as fast as possible. My hypothesis: In almost all cases, performance of interpreted languages rises with their level (high/low). Am I basically right with this? (If not, why?)

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  • Index out of range exception when using this query from C#

    - by jenifa
    I am using a calculation in my SQL query. How can I use that calculated field in C#? When I try, I get an index out of range exception. My query is: Select OwnerCompanyLog.olog_name,inlt_companyid,inlt_childcompid,inlt_effectinterest,inlt_percent,inlt_sharetype,inlt_shares,inlt_childbase,inlt_effdate, (inlt_percent * inlt_effectinterest)/100)eff from InterestLogTable INNER JOIN OwnerCompanyLog ON InterestLogTable.inlt_childcompid = OwnerCompanyLog.olog_companyid where inlt_companyid=5 Order By inlt_childcompid I want to use inlt_percent * inlt_effectinterest)/100 in my C# code: entity.ParentCompany = new List<Company>(); while (parentCompanyReader.Read()) { ParentCompany.Effect = parentCompanyReader["eff"].ToString(); entity.ParentCompany.Add(ParentCompany); } parentCompanyReader.Close(); But I got the error above.

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  • Does Adding more namespace in the code file affect performace ?

    - by Harikrishna
    If we imports more namespace in the code file(cs file) then it affects on perfomance ? Like we should add namespace in the cs file as needed. That is adding more namespace in the cs file affects performance ? Like using System; using System.Data.Sql; using System.Collections.Generic; using System.Data; using System.IO; using System.Linq; using System.Text.RegularExpressions; using System.Windows.Forms; using System.Xml; using System.Data.SqlClient; using System.ComponentModel;

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  • Query string problem if we use header

    - by avani-nature
    Hai frnds i am new to php actually i am facing following problems in coding please can anyone give the solution? Actually i am having one audio player and i am displaying some word dcoument if i click word document corresponding audio file should play actually when i click doc file it should pop ip with save as and open with for that i am using some header code also i am passing query string in the browser query string is not working if i use header can anyone give me a solution for it below is my code i am attaching <?php $f_name = $_POST["fn"]; $id = $_POST["id1"]; echo $id; //echo "../public_html/sites/default/files/ourfiles/$f_name"; $res2=db_query("select * from mt_files where id='".$id."' "); $row2=db_fetch_array($res2); $job_audio=$row2["audio_name"]; //echo $job_audio; //$job_audi=explode("/",$job_audio); //$job_audio=$job_audi[8]; $job_audio= "C:/xampp/htdocs/med/sites/default/files/audio/$job_audio"; //$job_audio= "C:/Documents and Settings/swuser/My Documents/$job_audio"; //echo $job_audio; echo "<object data='$job_audio' type='application/x-mplayer2' width='150' height='45'> <param name='src' value='$job_audio'> <param name='autoplay' value='true'> <param name='autoStart' value='1'> </object> "; $file = "../mts/sites/default/files/docs/$f_name"; if (file_exists($file)) { header('Content-Description: File Transfer'); header('Content-Type: application/octet-stream'); header('Content-Disposition: attachment; filename='.basename($file)); header('Content-Transfer-Encoding: binary'); header('Expires: 0'); header('Cache-Control: must-revalidate, post-check=0, pre-check=0'); header('Pragma: public'); header('Content-Length: ' . filesize($file)); ob_clean(); flush(); readfile($file); exit; } //The download table query goes here put the $f_name in insert into with the //time varible ?>

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  • Can I do this in only one query ?

    - by Paté
    Merry christmas everyone, I Know my way around SQL but I'm having a hard time figuring this one out. First here are my tables (examples) User id name friend from //userid to //userid If user 1 is friend with user 10 then you a row with 1,10. User 1 cannot be friend with user 10 if user 10 is not friend with user 1 so you have 1,10 10,1 It may look weird but I need those two rows per relations. Now I'm trying to make a query to select the users that have the most mutual friend with a given user. For example User 1 is friend with user 10,9 and 7 and user 8 is friend with 10,9 and 7 too ,I want to suggest user 1 to invite him (like facebook). I want to get like the 10 first people with the most mutual friend. The output would be like User,NumOfMutualFriends I dont know if that can be done in a single query ? Thanks in advance for any help.

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  • Understanding memory leak in Android app.

    - by sat
    After going through few articles about performance, Not able to get this statement exactly. "When a Drawable is attached to a view, the view is set as a callback on the drawable" Soln: "Setting the stored drawables’ callbacks to null when the activity is destroyed." What does that mean, e.g. In my app , I initialize an imageButton in onCreate() like this, imgButton= (ImageButton) findViewById(R.id.imagebtn); At later stage, I get an image from an url, get the stream and convert that to drawable, and set image btn like this, imgButton.setImageDrawable(drawable); According to the above statement, when I am exiting my app, say in onDestroy() I have to set stored drawables’ callbacks to null, not able to understand this part ! In this simple case what I have to set as null ? I am using Android 2.2 Froyo, whether this technique is required, or not necessary.

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  • One database or many?

    - by dsims
    I am developing a website that will manage data for multiple entities. No data is shared between entities, but they may be owned by the same customer. A customer may want to manage all their entities from a single "dashboard". So should I have one database for everything, or keep the data seperated into individual databases? Is there a best-practice? What are the positives/negatives for having a: database for the entire site (entity has a "customerID", data has "entityID") database for each customer (data has "entityID") database for each entity (relation of database to customer is outside of database) Multiple databases seems like it would have better performance (fewer rows and joins) but may eventually become a maintenance nightmare.

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  • Distributing cpu-bound compression jobs to multiple computers?

    - by barnaby
    The other day I needed to archive a lot of data on our network and I was frustrated I had no immediate way to harness the power of multiple machines to speed-up the process. I understand that creating a distributed job management system is a leap from a command-line archiving tool. I'm now wondering what the simplest solution to this type of distributed performance scenario could be. Would a custom tool always be a requirement or are there ways to use standard utilities and somehow distribute their load transparently at a higher level? Thanks for any suggestions.

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  • [MySQL] Optimize Query

    - by bordeux
    Hello. I have problem with optimize this query: SET @SEARCH = "dokumentalne"; SELECT SQL_NO_CACHE `AA`.`version` AS `Version` , `AA`.`contents` AS `Contents` , `AA`.`idarticle` AS `AdressInSQL` , `AA` .`topic` AS `Topic` , MATCH (`AA`.`topic` , `AA`.`contents`) AGAINST (@SEARCH) AS `Relevance` , `IA`.`url` AS `URL` FROM `xv_article` AS `AA` INNER JOIN `xv_articleindex` AS `IA` ON ( `AA`.`idarticle` = `IA`.`adressinsql` ) INNER JOIN ( SELECT `idarticle` , MAX( `version` ) AS `version` FROM `xv_article` WHERE MATCH (`topic` , `contents`) AGAINST (@SEARCH) GROUP BY `idarticle` ) AS `MG` ON ( `AA`.`idarticle` = `MG`.`idarticle` ) WHERE `IA`.`accepted` = "yes" AND `AA`.`version` = `MG`.`version` ORDER BY `Relevance` DESC LIMIT 0 , 30 Now, this query using ^ 20 seconds. How to optimize this? EXPLAIN gives this: 1 PRIMARY AA ALL NULL NULL NULL NULL 11169 Using temporary; Using filesort 1 PRIMARY ALL NULL NULL NULL NULL 681 Using where 1 PRIMARY IA ALL accepted NULL NULL NULL 11967 Using where 2 DERIVED xv_article fulltext topic topic 0 1 Using where; Using temporary; Using filesort This is example server with my data: user: bordeux_4prog password: 4prog phpmyadmin: http://phpmyadmin.bordeux.net/ chive: http://chive.bordeux.net/

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  • java virtual machine - how does it allocate resources?

    - by Will
    I am testing the performance of a data streaming system that supports continuous queries. This is how it works: - There is a polling service which sends data to my system. - As data passes into the system, each query evaluates based on a window of the stream at the current time. - The window slides as data passes in. My problem is this, when I add more queries to the system, I should expect the throughput to decrease because it can't cope the data rate. However, I actually observe an increase in throughput. I can't understand why this is the case and I am guessing that it's something to do with the way the JVM allocates CPU, memory etc. Can anyone shed any light to my problem?

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  • 2 table SQL Query weird results

    - by javArc
    Ok this is driving me nuts, I need to write an SQL query that will grab product information from 2 tables. The first table 'products' contains the productId, productname, quantityperunit and unitprice. Now I can search by productname and categoryname individually, but when I try to combine the 2 I get crazy results, Here's the query: "SELECT DISTINCT productId, productname, quantityperunit, unitprice FROM products pr, categories ca WHERE pr.categoryID = ca.categoryID AND ProductName LIKE '%" + searchTerm + "%' OR CategoryName LIKE '%" + searchTerm + "%' excuse the java style in there, here it is formatted better: SELECT DISTINCT productId, productname, quantityperunit, unitprice FROM products pr, categories ca WHERE pr.categoryID = ca.categoryID AND ProductName LIKE 'Tofu' OR CategoryName LIKE 'Tofu' any help would be appreciated.

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