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• SQL query - choosing 'last updated' record in a group, better db design?

  - by Jimmy

  Hi, Let's say I have a MySQL database with 3 tables: table 1: Persons, with 1 column ID (int) table 2: Newsletters, with 1 column ID (int) table 3: Subscriptions, with columns Person_ID (int), Newsletter_ID (int), Subscribed (bool), Updated (Datetime) Subscriptions.Person_ID points to a Person, and Subscription.Newsletter_ID points to a Newsletter. Thus, each person may have 0 or more subscriptions to 0 or more magazines at once. The table Subscriptions will also store the entire history of each person's subscriptions to each newsletter. If a particular Person_ID-Newsletter_ID pair doesn't have a row in the Subscriptions table, then it's equivalent to that pair having a subscription status of 'false'. Here is a sample dataset Persons ID 1 2 3 Newsletters ID 4 5 6 Subscriptions Person_ID Newsletter_ID Subscribed Updated 2 4 true 2010-05-01 3 4 true 2010-05-01 3 5 true 2010-05-10 3 4 false 2010-05-15 Thus, as of 2010-05-16, Person 1 has no subscription, Person 2 has a subscription to Newsletter 4, and Person 3 has a subscription to Newsletter 5. Person 3 had a subscription to Newsletter 4 for a while, but not anymore. I'm trying to do 2 kinds of query. A query that shows everyone's active subscriptions as of query time (we can assume that updated will never be in the future -- thus, this means returning the record with the latest 'updated' value for each Person_ID-Newsletter_ID pair, as long as Subscribed is true (if the latest record for a Person_ID-Newsletter_ID pair has a Subscribed status of false, then I don't want that record returned)). A query that returns all active subscriptions for a specific newsletter - same qualification as in 1. regarding records with 'false' in the Subscribed column. I don't use SQL/databases often enough to tell if this design is good, or if the SQL queries needed would be slow on a database with, say, 1M records in the Subscriptions table. I was using the Visual query builder tool in Visual Studio 2010 but I can't even get the query to return the latest updated record for each Person_ID-Newsletter_ID pair. Is it possible to come up with SQL queries that don't involve using subqueries (presumably because they would become too slow with a larger data set)? If not, would it be a better design to have a separate Subscriptions_History table, and every time a subscription status for a Person_ID-Newsletter-ID pair is added to Subscriptions, any existing record for that pair is moved to Subscriptions_History (that way the Subscriptions table only ever contains the latest status update for any Person_ID-Newsletter_ID pair)? I'm using .net on Windows, so would it be easier (or the same, or harder) to do this kind of queries using Linq? Entity Framework? Thanks!

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• hibernate executeUpdate IndexOutOfBounds

  - by luke

  I am trying to use an HQL to perform a simple update in hibernate, but i can't seem to get it to work. i have a query template defined as: private static final String CHANGE_DEVICE_STATUS = "UPDATE THING" +"SET ACTIVE = ? " +"WHERE ID = ?"; and then i try to execute it like this: Session s = HibernateSessionFactory.getSession(); Query query = s.createQuery(CHANGE_DEVICE_STATUS); query.setBoolean(0, is_active); query.setLong(1, id); query.executeUpdate(); But now i get this error: java.lang.IndexOutOfBoundsException: Index: 0, Size: 0 at java.util.ArrayList.RangeCheck(ArrayList.java:547) at java.util.ArrayList.get(ArrayList.java:322) at org.hibernate.hql.ast.HqlSqlWalker.postProcessUpdate(HqlSqlWalker.java:390) at org.hibernate.hql.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:164) at org.hibernate.hql.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:189) at org.hibernate.hql.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:130) at org.hibernate.hql.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:83) at org.hibernate.impl.SessionFactoryImpl.getQuery(SessionFactoryImpl.java:427) at org.hibernate.impl.SessionImpl.getQueries(SessionImpl.java:884) at org.hibernate.impl.SessionImpl.executeUpdate(SessionImpl.java:865) at org.hibernate.impl.QueryImpl.executeUpdate(QueryImpl.java:89) .... what am i doing wrong here? I am using hibernate 3.0 UPDATE i changed it to Query query = s.createQuery(CHANGE_DEVICE_STATUS); query.setBoolean(1, is_active); query.setLong(2, id);//<---throws here query.executeUpdate(); without changing anything else but the parameter indexes and i got this: java.lang.IllegalArgumentException: Positional parameter does not exist: 2 in query: UPDATE DEVICE_INSTANCES SET ACTIVE = ? WHERE DEVICE_INSTANCE_ID = ? at org.hibernate.impl.AbstractQueryImpl.setParameter(AbstractQueryImpl.java:194) at org.hibernate.impl.AbstractQueryImpl.setLong(AbstractQueryImpl.java:244) ...

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• How can you access two identically-named columns in a MySQL LEFT JOIN query?

  - by George Edison

  I have two tables. table_x: id INT(11) tag INT(11) table_tags: id INT(11) name VARCHAR(255) Then I use PHP to perform the following query: SELECT * FROM table_x LEFT JOIN table_tags ON table_x.tag = table_tags.id The only problem is: how do I access table_x.id and table_tags.id in the results? Here is the PHP code: $query = "SELECT * FROM table_x LEFT JOIN table_tags ON table_x.tag = table_tags.id"; $results = mysql_query($query); while($row = mysql_fetch_array($results)) { // how do I now access table_x.id and table_tags.id ??? }

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• How to compress/decompress a long query string in PHP?

  - by jodeci

  I doubt if this is encryption but I can't find a better phrase. I need to pass a long query string like this: http://test.com/test.php?key=[some_very_loooooooooooooooooooooooong_query_string] The query string contains NO sensitive information so I'm not really concerned about security in this case. It's just...well, too long and ugly. Is there a library function that can let me encode/encrypt/compress the query string into something similar to the result of a md5() (similar as in, always a 32 character string), but decode/decrypt/decompress-able?

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• How can I do this Aggrigate, group by, in query in LINQ?

  - by Ólafur Waage

  Please do not give me a full working example, I want to know how this is done rather than to get some code I can copy paste This is the query I need, and can't for the life of me create it in LINQ. SELECT * FROM dbo.Schedules s, dbo.Videos v WHERE s.VideoID = v.ID AND s.ID IN ( SELECT MAX(ID) FROM dbo.Schedules WHERE ChannelID = 1 GROUP BY VideoID ) ORDER BY v.Rating DESC, s.StartTime DESC I have the "IN" query in LINQ I think, it's something like this var uniqueList = from schedule in db.Schedules where schedule.ChannelID == channelID group schedule by schedule.VideoID into s select new { id = s.Max(i => i.ID) }; It is possibly wrong, but now I can not check in another query for this in a where clause uniqueList.Contains(schedule.ID) There is possibly a better way to write this query, if you have any idea I would love some hints. I get this error and it's not making much sense. The type arguments for method 'System.Linq.Queryable.Contains(System.Linq.IQueryable, TSource)' cannot be inferred from the usage. Try specifying the type arguments explicitly.

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• What is the performance difference between blocks and callbacks?

  - by Don

  One of the things that block objects, introduced in Snow Leopard, are good for is situations that would previously have been handled with callbacks. The syntax is much cleaner for passing context around. However, I haven't seen any information on the performance implications of using blocks in this manner. What, if any, performance pitfalls should I look out for when using blocks, particularly as a replacement for a C-style callback?

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• How to write following MongoDB query in C# Driver?

  - by user3043457

  I wrote the exact query I need in Mongo console, but I'm having trouble rewriting it in C# driver. Here's a sample of the document, it's simple dictionary: { "_id" : ObjectId("539716bc101c588f941e2c27"), "_t" : "DictionaryDocument", "CsvSeparator" : ",", "SelectedAccounts" : "0", ... } Here's the query: db.settings.find({"SelectedAccounts" :{$exists:true}},{"SelectedAccounts":1, "_id":0} ) Now, I got the first part, Find with exists working, but how to write the second parameter in C# driver? I'd just like a single string as a result, not entire document. Here's C# code I got so far: _collection.FindOneAs(typeof(DictionaryDocument), Query.Exists(key)); key in this case is "SelectedAccounts". I'd like the query to filter and return only the data I need, I don't want to return all the results and search on the C# side. EDIT: I wouldn't mind if _id was passed back, but I don't need it. So only this part would work if it could be converted in C#: db.settings.find({"SelectedAccounts" :{$exists:true}},{"SelectedAccounts":1} )

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• What logic can be applied to create the Insert query from given Audit table?

  - by Parth

  i need to create a PHP script to create the insert query to insert in a table, The table from which I need to fetch out the data to create insert query is given below.. The query has to be like this INSERT INTO table_name (field1,field2, field3...) values('newvalue','newvalue','newvalue',....) Please Help... Thanks

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• How to find specific row in MySQL query result?

  - by Šime Vidas

  So I do this to retrieve my entire table: $result = mysql_query( 'SELECT * FROM mytable' ); Then, in another part of my PHP-page, I do another query (for a specific row): $result2 = mysql_query( 'SELECT * FROM mytable WHERE id = ' . $id ); $row = mysql_fetch_array( $result2 ); So, I'm performing two querys. However, I don't really have to do that, do I? I mean, the row that I'm retrieving in my second query already is present in $result (the result of my first query), since it contains my entire table. Therefore, instead of doing the second query, I would like to extract the desired row from $result directly (while keeping $result itself in tact). How would I do that? OK, so this is how I've implemented it: function getRowById ( $result, $id ) { while ( $row = mysql_fetch_array( $result ) ) { if ( $row['id'] == $id ) { mysql_data_seek( $result, 0 ); return $row; } } }

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• Switching from PHP to Ruby - is it the answer to performance?

  - by Industrial

  Hi everyone, I get more often the answer, when asking performance related stuff regarding PHP applications, that PHP really isn't the language for high-performance applications, and that a compiled language really is the way to go. The only thing holding me back to PHP is that it's what I have learned to work with for some while now and the development is quite rapid. So, is PHP a thing of the past and should be put aside in web applications in favour of Ruby, for instance? Thanks

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• How to get multiple counts with one SQL query?

  - by Crobzilla

  I am wondering how to write this query. I know this actual syntax is bogus, but it will help you understand what I am wanting. I need it in this format, because it is part of a much bigger query. SELECT distributor_id, COUNT(*) AS TOTAL, COUNT(*) WHERE level = 'exec', COUNT(*) WHERE level = 'personal' I need this all returned in one query. Also, it need to be in one row, so the following won't work: 'SELECT distributor_id, COUNT(*) GROUP BY distributor_id'

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• Is there a command to test an SQL query without executing it? ( MySQL or ANSI SQL )

  - by Petruza

  Is there anything like this: TEST DELETE FROM user WHERE somekey = 45; That can return any errors, for example that somekey doesn't exist, or some constraint violation or anything, and reporting how many rows would be affected, but not executing the query? I know you can easily turn any query in a select query that has no write or delete effect in any row, but that can lead to errors and it's not very practical if you want to test and debug many queries.

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• how can add an extra select in this query?

  - by BulgedSnowy

  i've three tables related. images: id | filename | filesize | ... nodes: image_id | tag_id tags: id | name And i'm using this query to search images containing x tags SELECT images.* FROM images INNER JOIN nodes ON images.id = nodes.image_id WHERE tag_id IN (SELECT tags.id FROM tags WHERE tags.tag IN ("tag1","tag2")) GROUP BY images.id HAVING COUNT(*)= 2 The problem is that i need to retrieve also all images contained by the retrieved image, and i need this in the same query. This the actual query wich search retrieve all tags contained by the image: SELECT tag FROM nodes JOIN tags ON nodes.tag_id = tags.id WHERE image_id = images.id and nodes.private = images.private ORDER BY tag How can i mix this two to have only one query?

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• How to change language/region in a YQL search.spelling/search.suggestion query?

  - by Francisco Noriega

  Hello, I'm trying to use YQL's spelling and search suggestions, but as much as I try I cant find a way to change the language/region for the query, how is this done? I want to look for spelling/suggestions in spanish/mexico ("es-MX") I'm pretty happy with the results I get for queries in English, but when looking in Spanish I get no results: select * from search.suggest where query="dolor de cabeza" <?xml version="1.0" encoding="UTF-8"?> <query xmlns:yahoo="http://www.yahooapis.com/v1/base.rng" yahoo:count="0" yahoo:created="2010-11-22T17:41:13Z" yahoo:lang="en-US"> <results/> </query> I've looked around for a way to change yahoo:lang="en-US" to yahoo:lang="es-MX" but I cant find andy documentation about it. Thanks!

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• How to query from MEDIA provider with "group by" option?

  - by gkshope

  I'm a newbie to Android. Actually, I want to query data from Media provider with Content provider & content resolver. c = mContent.query(CONTENT_URI,projection,where,null,null); My question is, how can I query data from media provider as below using a GROUP BY clause: select DISTINCT _id, count(_id), _data FROM aaa_table WHERE _data LIKE "A" OR _data LIKE "B" GROUP BY _id; I have tried setting projection and where as follows: final String[] projection = new String[] { "_id", "COUNT ("+ _id +")" , "_data" }; and where: _data LIKE "A" OR _data LIKE "B" but, I couldn't find how to set the query option GROUP BY _id. Please help me.

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• Spotlight query to search for all archives and ISO files that their names do not end in bin

  - by Bytecode Ninja

  The following Spotlight query, correctly returns all archive and ISO files on my system: kind:iso OR kind:archive However, Spotlight treats .bin files as archives too and returns .bin files in the results as well. How can I modify the above query and exclude files that end in bin from the result? I tried the following query but it is not working: (kind:iso OR kind:archive) AND NOT name:*bin Thanks in advance.

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• EF Query using .Contains() and .ToLowerInvariant() Results in no matches when match is found at the end of a string

  - by MyNameIsJob

  Is it possible to step into a linq query? I have a linq to entity framework 4 query in it's simplest form: List = List.Where(f => f.Value.ToString().ToLowerInvariant().Contains(filter.ToLowerInvariant())); It's a query against an Entity Framework DbContext and I'm having trouble seeing why it works for something like: List searching for 001 yields no results against the following list Test001 Test002 Test003 Test004 However any other search yields results (Such as t00 or Test) Update Basically I'm looking for why a query such as the above wouldn't return a result when I'm using a contains and the value matches the end of a string vs just the middle or begining. It's really confusing. OK, it appears to have something to do with ToLowerInvariant() - when I removed that method it works just fine.

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• Doctrine: how to create a query using "LIKE REPLACE" ?

  - by user248959

  Hi, this SQL clause is working OK: SELECT * FROM `sf_guard_user` WHERE nombre_apellidos LIKE REPLACE('Mar Sanz',' ','%') Now I'm trying to write this query for Doctrine. I have tried this: $query->andWhere(sprintf('%s.%s LIKE REPLACE (?," ","%")', $query->getRootAlias(), $fieldName), 'Mar Sanz')); but I get this error: Warning: sprintf() [function.sprintf]: Too few arguments Any idea? Regards Javi

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• PHP - How to display other values, when a query is limited by 3?

  - by Dodi300

  Hello. Can anyone tell me how to display the other values, when a query is limited my 3. In this question I asked how to order and limit values, but now I want to show the others in another query. How would I go about doing this? Here's the code I used before: $query = "SELECT gmd FROM account ORDER BY gmd DESC LIMIT 3"; $result = mysql_query($query); while($row = mysql_fetch_array($result, MYSQL_ASSOC)) { } Thanks!

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• Why is Zend Framework (Zend_Db_table) rejecting this SQL Query?

  - by Michael T. Smith

  I'm working on a simple JOIN of two tables (urls and companies). I am using this query call: print $this->_db->select()->from(array('u' => 'urls'), array('id', 'url', 'company_id')) ->join(array('c' => 'companies'), 'u.company_id = c.id'); which is out putting this query: SELECT `u`.`id`, `u`.`url`, `u`.`company_id`, `c`.* FROM `urls` AS `u` INNER JOIN `companies` AS `c` ON u.company_id = c.id Now, I'd prefer the c.* to not actually appear, but either way it doesn't matter. ZF dies with this error: SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 1" but I can run that query perfectly fine in my MySQL CLI. Any ideas how to fix up this query?

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• how to write oracle two instance information in single query?

  - by rsaravanakumar

  i using oracle 10g database, i installed two instance in my machine(dev and dev10g), i using query "select instance_name,status from v$instance" this query return one instance information but i need two (dev and dev10g) instance information, how i write a query. it is possible without using dblink. pls help me.

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• Can anyone help me with a complex sum, 3 table join mysql query?

  - by Scarface

  Hey guys I have a query and it works fine, but I want to add another table to the mix. The invite table I want to add has two fields: username and user_invite. Much like this site, I am using a point system to encourage diligent users. The current query which is displayed below adds the up votes and down votes based on the user in question: $creator. I want to count the number of entries for that same user from the invite table, and add 50 for each row it finds to the current output/sum of my query. Is this possible with one query, or do I need two? "SELECT *, SUM(IF(points_id = \"1\", 1,0))-SUM(IF(points_id = \"2\", 1,0)) AS 'total' FROM points LEFT JOIN post ON post.post_id=points.points_id WHERE post.creator='$creator'"

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• How to deal with the Hibernate hql multi-join query result in an Object-Oriented Way?

  - by EugeneP

  How to deal with the Hibernate hql multi-join query result in an Object-Oriented Way? As I see it returns a list of Objects. yes, it is tricky and only you who write the query know what should the query return (what objects). But are there ways to simplify things, so that it returned specific objects with no need in casting Object to a specific class according to its position in the query ? Maybe Spring can simplify things here? It has the similar functionality for JDBC, but I don't see if it can help in a similar way with Hibernate.

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• How do you query a MySQL table columns highest entry and store it in a variable.

  - by user315819

  How do you query a MySQL table columns highest entry and store it in a variable. Here is what I have but it is not working. $query = "SELECT MAX(date) FROM Records WHERE ips='$currentip'"; $result = mysql_query($query) or die(mysql_error()); echo $result;

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• Visual Studio 2010 Service Pack 1 Released

  - by krislankford

  The VS 2010 SP 1 release was simultaneous to the release of TFS 2010 SP1 and includes support for the Project Server Integration Feature Pack and updates to .NET Framework 4.0. The complete Visual Studio SP1 list including Test and Lab Manager: http://support.microsoft.com/kb/983509 The release addresses some of the most requested features from customers of Visual Studio 2010 like better help support IntelliTrace support for 64bit and SharePoint Silverlight 4 Tools in the box unit testing support on .NET 3.5 a new performance wizard for Silverlight Another major addition is the announcement of Unlimited Load Testing for Visual Studio 2010 Ultimate with MSDN Subscribers! The benefits of Visual Studio 2010 Load Test Feature Pack and useful links: Improved Overall Software Quality through Early Lifecycle Performance Testing: Lets you stress test your application early and throughout its development lifecycle with realistically modeled simulated load. By integrating performance validations early into your applications, you can ensure that your solution copes with real-world demands and behaves in a predictable manner, effectively increasing overall software quality. Higher Productivity and Reduced TCO with the Ability to Scale without Incremental Costs: Development teams no longer have to purchase Visual Studio Load Test Virtual User Pack 2010. Download the Visual Studio 2010 Load Test Feature Pack Deployment Guide Get started with stress and performance testing with Visual Studio 2010 Ultimate: Quality Solutions Best Practice: Enabling Performance and Stress Testing throughout the Application Lifecycle Hands-On-Lab: Introduction to Load Testing with ASP.NET Profile in Visual Studio 2010 How-Do-I videos: Use ASP.NET Profiler in Load Tests Use Network Emulation in Load Tests VHD/VPC walkthrough: Getting Started with Load and Performance Testing Best Practice guidance: Visual Studio Performance Testing Quick Reference Guide

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