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  • Insert statement with where clause.

    - by debraj
    I had a table with unique Date_t1 date type field, but in Table description field is not mentioned as unique, now while inserting new row i need to validate if date exist or not, If already exist i should not allow to make changes on that row, neither a new row needs to be created, Any idea how to resolve this problem in efficient way,

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  • Should the code being tested compile to a DLL or an executable file?

    - by uriDium
    I have a solution with two projects. One for project for the production code and another project for the unit tests. I did this as per the suggestions I got here from SO. I noticed that in the Debug Folder that it includes the production code in executable form. I used NUnit to run the tests after removing the executable and they all fail trying to find the executable. So it definitely is trying to find it. I then did a quick read to find out which is better, a DLL or an executable. It seems that an DLL is much faster as they share memory space where communication between executables is slower. Unforunately our production code needs to be an exectuable. So the unit tests will be slightly slower. I am not too worried about that. But the project does rely on code written in another library which is also in executable format at the moment. Should the projects that expose some sort of SDK rather be compiled to an DLL and then the projects that use the SDK be compiled to executable?

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  • Question about Cost in Oracle Explain Plan

    - by Will
    When Oracle is estimating the 'Cost' for certain queries, does it actually look at the amount of data (rows) in a table? For example: If I'm doing a full table scan of employees for name='Bob', does it estimate the cost by counting the amount of existing rows, or is it always a set cost?

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  • Is it wise to use temporary tables?

    - by Industrial
    Hi guys, We have a mySQL database table for products. We are utilizing a cache layer to reduce database load, but we think that it's a good idea to minimize the actual data needed to be stored in the cache layer to speed up the application further. All the products in the database, that is visible to visitors have a price attached to them: The prices are stored in a different table, called prices . There are multiple price categories depending on which discount level each visitor (customer) applies to. From time to time, there are campaigns which means that a special price for each product is available. The special prices are stored in a table called specials. Is it a bad to make a temp table that binds the tables together? It would only have the neccessary information and would ofcourse be cached. -------------|-------------|------------ | productId | hasPrice | hasSpecial -------------|-------------|------------ 1 | 1 | 0 2 | 1 | 1 By doing such, it would be super easy to know if the specific product really has a price, without having to iterate through the complete prices or specials table each time a product should be listed or presented. Are temp tables a common thing for web applications or is it just bad design?

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  • Queue-like data structure with fast search and insertion

    - by Max
    I need a datastructure with the following properties: It contains integer numbers, no duplicates. After it reaches the maximal size the first element is removed. So if the capacity is 3, then this is how it would look when putting in it sequential numbers: {}, {1}, {1, 2}, {1, 2, 3}, {2, 3, 4}, {3, 4, 5} etc. Only two operations are needed: inserting a number into this container (INSERT) and checking if the number is already in the container (EXISTS). The number of EXISTS operations is expected to be approximately 2 * number of INSERT operations. I need these operations to be as fast as possible. What would be the fastest data structure or combination of data structures for this scenario?

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  • Create MySQL user and database from PHP

    - by snaken
    Hi, Is there a way to create a new MySQL database, a new MySQL user and give the new user priviledges on the new database all using PHP? I've seen examples where mysql_query is used like this: mysql_query("CREATE DATABASE ".$dbname)or die(mysql_error()); but i don't see how this would work as there's no database connection. Help please!

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  • Java NIO Servlet to File

    - by Gandalf
    Is there a way (without buffering the whole Inputstream) to take the HttpServletRequest from a Java Servlet and write it out to a file using all NIO? Is it even worth trying? Will it be any faster reading from a normal java.io stream and writing to a java.nio Channel or do they both really need to be pure NIO to see a benefit? Thanks.

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  • Unknown column even thoug it exits

    - by george
    I have SELECT servisler.geo_location, servisler.ADRES_MERKEZ, servisler.ADRES_ILCE, servisler.ADRES_IL, servisler.FIRMA_UNVANI, servisler.ADRES_ISTEL, servisler.YETKILI_ADISOYADI, urun_gruplari.GRUP_ADI FROM servisler INNER JOIN urun_gruplari ON kullanici_cihaz.URUN_GRUP_NO= urun_gruplari.RECNO INNER JOIN kullanici ON kullanici.SERVIS_RECNO = servisler.RECNO INNER JOIN kullanici_cihaz ON kullanici.RECNO = kullanici_cihaz.KUL_RECNO AND kullanici_cihaz.URUN_GRUP_NO = urun_gruplari.RECNO where kullanici.kullanici = 'MAR.EDI.003' but it says [Err] 1054 - Unknown column 'kullanici_cihaz.URUN_GRUP_NO' in 'on clause' enen though the column exits. What is its problem? schema Server version: 5.1.33-community-log

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  • What's the fastest way to check if a word from one string is in another string?

    - by Mike Trpcic
    I have a string of words; let's call them bad: bad = "foo bar baz" I can keep this string as a whitespace separated string, or as a list: bad = bad.split(" "); If I have another string, like so: str = "This is my first foo string" What's the fasted way to check if any word from the bad string is within my comparison string, and what's the fastest way to remove said word if it's found? #Find if a word is there bad.split(" ").each do |word| found = str.include?(word) end #Remove the word bad.split(" ").each do |word| str.gsub!(/#{word}/, "") end

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  • MySQL LEFT JOIN, INNER JOIN etc, complicated query, PHP + MySQL for a forum

    - by Sven Eriksson
    So I've got a little forum I'm trying to get data for, there are 4 tables, forum, forum_posts, forum_threads and users. What i'm trying to do is to get the latest post for each forum and giving the user a sneak peek of that post, i want to get the number of posts and number of threads in each forum aswell. Also, i want to do this in one query. So here's what i came up with: SELECT lfx_forum_posts.*, lfx_forum.*, COUNT(lfx_forum_posts.pid) as posts_count, lfx_users.username, lfx_users.uid, lfx_forum_threads.tid, lfx_forum_threads.parent_forum as t_parent, lfx_forum_threads.text as t_text, COUNT(lfx_forum_threads.tid) as thread_count FROM lfx_forum LEFT JOIN (lfx_forum_threads INNER JOIN (lfx_forum_posts INNER JOIN lfx_users ON lfx_users.uid = lfx_forum_posts.author) ON lfx_forum_threads.tid = lfx_forum_posts.parent_thread AND lfx_forum_posts.pid = (SELECT MAX(lfx_forum_posts.pid) FROM lfx_forum_posts WHERE lfx_forum_posts.parent_forum = lfx_forum.fid GROUP BY lfx_forum_posts.parent_forum) ) ON lfx_forum.fid = lfx_forum_posts.parent_forum GROUP BY lfx_forum.fid ORDER BY lfx_forum.fid ASC This get the latest post in each forum and gives me a sneakpeek of it, the problem is that lfx_forum_posts.pid = (SELECT MAX(lfx_forum_posts.pid) FROM lfx_forum_posts WHERE lfx_forum_posts.parent_forum = lfx_forum.fid GROUP BY lfx_forum_posts.parent_forum) Makes my COUNT(lfx_forum_posts.pid) go to one (aswell as the COUNT(lfx_forum_threads.tid) which isn't how i would like it to work. My question is: is there some somewhat easy way to make it show the correct number and at the same time fetch the correct post info (the latest one that is)? If something is unclear please tell and i'll try to explain my issue further, it's my first time posting something here.

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  • How to decide on what hardware to deploy web application

    - by Yuval A
    Suppose you have a web application, no specific stack (Java/.NET/LAMP/Django/Rails, all good). How would you decide on which hardware to deploy it? What rules of thumb exist when determining how many machines you need? How would you formulate parameters such as concurrent users, simultaneous connections and DB read/write ratio to a decision on how much, and which, hardware you need? Any resources on this issue would be very helpful...

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  • JVM tuning on Amazon EC2

    - by Shadowman
    We will be deploying a production application to Amazon EC2 very shortly. Initially, we'll just be using a "small" instance, but have plans to scale up not long afterwards. My question is, has any investigation been done on JVM tuning for the EC2 environment? Are there any specific changes that we should make to our JVM parameters to compensate for quirks/characteristics of Amazon EC2? Or, do the normal tuning methodologies apply here as they would in a physical environment? Our application will be deployed on Tomcat 6.x. It is built using JBoss Seam 2.2.x, and uses PostgreSQL 8.x as the backend database. Any advice you can give is greatly appreciated!

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  • iPhone and Vertex Buffer Objects

    - by dancer
    I've just started playing around with opengl es on the iphone the past couple of weeks and i'm looking at refactoring some of my code to use Vertex Buffer Objects(VBO). Before I do though I would like to make sure it'll be worth it. The problem is that afaik the only reason you create VBO's is to shift a chunk of data onto the graphics card so that it doesn't need to be retrieved from system ram when it's used. The iPhone however does not have any dedicated ram that I'm aware of so i'm struggling to see why I would benefit at all from using VBO's. I have seen talk around the internet with conflicting opinions and apple certainly want dev's to use it so there's probably still a reason to use them but just wanted to see if anyone on SO had an opinion to add.

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  • How to match multiple field in mySQL

    - by Mint
    Im trying to match forum_id with several different forum_id's, something like forum_id = 5,7,12,43,63,78 I currently have this code: SELECT topic_title, topic_id, forum_id FROM $MYSQL_TOPIC WHERE topic_title LIKE '%%%s%%' AND forum_id = 5 LIMIT 50 (using mysql_real_escape_string and sprintf) I tried: forum_id = 5 OR 7 forum_id = 5|7 forum_id = 5 AND 7 forum_id = 5 & 7 But none of them will match them all and therefore search though them all.

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  • Suggested (simple) approach for drawing large numbers of visual elements in WPF?

    - by Ender
    I'm writing an interface that features a large (~50000px width) "canvas"-type area that is used to display a lot of data in a fairly novel way. This involves lots of lines, rectangles, and text. The user can scroll around to explore the entire canvas. At the moment I'm just using a standard Canvas panel with various Shapes placed on it. This is nice and easy to do: construct a shape, assign some coordinates, and attach it to the Canvas. Unfortunately, it's pretty slow (to construct the children, not to do the actual rendering). I've looked into some alternatives, it's a bit intimidating. I don't need anything fancy - just the ability to efficiently construct and place objects in a coordinate plane. If all I get are lines, colored rectangles, and text, I'll be happy. Do I need Geometry instances inside of Geometry Groups inside of GeometryDrawings inside of some Panel container? Note: I'd like to include text and graphics (i.e. colored rectangles) in the same space, if possible.

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  • PHP fastest method of reading server response

    - by Peter John
    Hi there, im having some real problems with the lag produced by using fgets to grab the server's response to some batch database calls im making. Im sending through a batch of say, 10,000 calls and ive tracked the lag down to fgets causing the hold up in the speed of my application as the response for each call needs to be grabbed. I have found this thread http://bugs.php.net/bug.php?id=32806 which explains the problem quite well, but hes reading a file, not a server response so fread could be a bit tricky as i could get part of the next line, and extra stuff which i dont want. Any help much appreciated!

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  • How to query AD to get name email from lan id

    - by Kumar
    I have some code in asp.net ( kindly given by someone else ) to query AD to get user name and email etc. using System.DirectoryServices; using System.DirectoryServices.ActiveDirectory; using ActiveDs; DirectorySearcher search = new DirectorySearcher(new DirectoryEntry(), string.Format("(samaccountname={0})", id)); if (search == null) return id; if (search.FindOne() == null) return id; DirectoryEntry usr = search.FindOne().GetDirectoryEntry(); IADsUser oUsr = (IADsUser)usr.NativeObject; return string.Format("{0} {1}", usr.Properties["givenname"].Value, usr.Properties["sn"].Value); However this requires impersonation with an id that's required to be changed every 2 weeks and then updated in the web.config which is often forgotten Is there any non impersonation code to achieve the same result ? UPDATE - it's a config tool and it looks up name, email id etc. I like the service a/c idea Q - How is it possible to run ( impersonate ) just the AD code with a "service" a/c ? any samples/code ? how do you impersona

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  • Node & Redis: Crucial Design Issues in Production Mode

    - by Ali
    This question is a hybrid one, being both technical and system design related. I'm developing the backend of an application that will handle approx. 4K request per second. We are using Node.js being super fast and in terms of our database struction we are using MongoDB, with Redis being a layer between Node and MongoDB handling volatile operations. I'm quite stressed because we are expecting concurrent requests that we need to handle carefully and we are quite close to launch. However I do not believe I've applied the correct approach on redis. I have a class Student, and they constantly change stages(such as 'active', 'doing homework','in lesson' etc. Thus I created a Redis DB for each state. (1 for being 'active', 2 for being 'doing homework'). Above I have the structure of the 'active' students table; xa5p - JSON stringified object #1 pQrW - JSON stringified object #2 active_student_table - {{studentId:'xa5p'}, {studentId:'pQrW'}} Since there is no 'select all keys method' in Redis, I've been suggested to use a set such that when I run command 'smembers' I receive the keys and later on do 'get' for each id in order to find a specific user (lets say that age older than 15). I've been also suggested that in fact I used never use keys in production mode. My question is, no matter how 'conceptual' it is, what specific things I should avoid doing in Node & Redis in production stage?. Are they any issues related to my design? Students must be objects and I sure can list them in a list but I haven't done yet. Is it that crucial in production stage?

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  • Python faster way to read fixed length fields form a file into dictionary

    - by Martlark
    I have a file of names and addresses as follows (example line) OSCAR ,CANNONS ,8 ,STIEGLITZ CIRCUIT And I want to read it into a dictionary of name and value. Here self.field_list is a list of the name, length and start point of the fixed fields in the file. What ways are there to speed up this method? (python 2.6) def line_to_dictionary(self, file_line,rec_num): file_line = file_line.lower() # Make it all lowercase return_rec = {} # Return record as a dictionary for (field_start, field_length, field_name) in self.field_list: field_data = file_line[field_start:field_start+field_length] if (self.strip_fields == True): # Strip off white spaces first field_data = field_data.strip() if (field_data != ''): # Only add non-empty fields to dictionary return_rec[field_name] = field_data # Set hidden fields # return_rec['_rec_num_'] = rec_num return_rec['_dataset_name_'] = self.name return return_rec

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  • Calculate the retrieved rows in database Visual C#

    - by Tanya Lertwichaiworawit
    I am new in Visual C# and would want to know how to calculate the retrieved data from a database. Using the above GUI, when "Calculate" is click, the program will display the number of students in textBox1, and the average GPA of all students in textBox2. Here is my database table "Students": I was able to display the number of students but I'm still confused to how I can calculate the average GPA Here's my code: private void button1_Click(object sender, EventArgs e) { string connection = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Database1.accdb"; OleDbConnection connect = new OleDbConnection(connection); string sql = "SELECT * FROM Students"; connect.Open(); OleDbCommand command = new OleDbCommand(sql, connect); DataSet data = new DataSet(); OleDbDataAdapter adapter = new OleDbDataAdapter(command); adapter.Fill(data, "Students"); textBox1.Text = data.Tables["Students"].Rows.Count.ToString(); double gpa; for (int i = 0; i < data.Tables["Students"].Rows.Count; i++) { gpa = Convert.ToDouble(data.Tables["Students"].Rows[i][2]); } connect.Close(); }

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  • Merging MySQL row entries into a single row

    - by Derrick
    I've got two tables, one for listings and another representing a list of tags for the listings table. In the listings table the tag ids are stored in a field called tags as 1-2-3-. This has worked out very well for me (regular expressions and joins to separate and display the data), but I now need to pull the titles of those tags into a single row. See below. listings table id tags 1 1-2-3- 2 4-5-6- tags table id title 1 pig 2 dog 3 cat 4 mouse 5 elephant 6 duck And what I need to produce out of the listings table is: id tags 2 mouse, elephant, duck

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