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  • How do I select a random record efficiently in MySQL?

    - by user198729
    mysql> EXPLAIN SELECT * FROM urls ORDER BY RAND() LIMIT 1; +----+-------------+-------+------+---------------+------+---------+------+-------+---------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------+------+---------------+------+---------+------+-------+---------------------------------+ | 1 | SIMPLE | urls | ALL | NULL | NULL | NULL | NULL | 62228 | Using temporary; Using filesort | +----+-------------+-------+------+---------------+------+---------+------+-------+---------------------------------+ The above doesn't qualify as efficient,how should I do it properly?

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  • Running an application from an USB device...

    - by Workshop Alex
    I'm working on a proof-of-concept application, containing a WCF service with console host and client, both on a single USB device. On the same device I will also have the client application which will connect to this service. The service uses the entity framework to connect to the database, which in this POC will just return a list of names. If it works, it will be used for a larger project. Creating the client and service was easy and this works well from USB. But getting the service to connect to the database isn't. I've found this site, suggesting that I should modify machine.config but that stops the XCopy deployment. This project cannot change any setting of the PC, so this suggestion is bad. I cannot create a deployment setup either. The whole thing just needs to run from USB disk. So, how do I get it to run? (The service just selects a list of names from the database, which it returns to the client. If this POC works, it will do far more complex things!)

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  • Alternative to subqueries

    - by Juanma
    I'm using Mysql 5.1, and have this query, is there a way to not use the subqueries and accomplish the same result? SELECT oref.affiliate_id, ROUND(sum( oph.amount ) * 0.10 ,2) AS tsum FROM operators_referer AS oref LEFT JOIN operators_payments_history AS oph ON oref.operator_id = oph.operator_id WHERE oref.affiliate_id = 28221 AND ( oph.date_paid > ( SELECT MAX(aph.date_paid) FROM affiliates_payments_history AS aph WHERE aph.operator_id = oref.affiliate_id ) OR ( SELECT MAX(aph.date_paid) FROM affiliates_payments_history AS aph WHERE aph.operator_id = oref.affiliate_id ) is NULL )

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  • counting employee attendance

    - by jjj
    i am trying to write a statment for counting the employees attendance and execute thier id , name and the days that he has working on the last 3 months by counting the duplicate id on NewTimeAttendance for month 1 , 2 and 3 .. i tried to count : Select COUNT(employeeid) from NewTimeAttendance where employeeid=1 and (month=1 or month =2 or month = 3) This is absolutely working ,but just for one employee... the secound try: SELECT COUNT(NewEmployee.EmployeeID) FROM NewEmployee INNER JOIN NewTimeAttendance ON NewEmployee.EmployeeID = NewTimeAttendance.EmployeeID and (month=1 or month =2 or month = 3) This is working , but it counts all employees .. and i want it to execute each EmployeeId, EmployeeName and number of days as new record last try: (before you see the code ... it is wrong ..but i am trying) for i in 0..27 loop SELECT COUNT(NewEmployee.EmployeeID),NewEmployee.EmployeeId,EmployeeName FROM NewEmployee INNER JOIN NewTimeAttendance ON NewEmployee.EmployeeID(i) = NewTimeAttendance.EmployeeID and (month=1 or month =2 or month = 3) end loop i realy need help...thanks in advance

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  • Which MySql line is faster:

    - by Camran
    I have a classified_id variable which matches one document in a MySql table. I am currently fetching the information about that one record like this: SELECT * FROM table WHERE table.classified_id = $classified_id I wonder if there is a faster approach, for example like this: SELECT 1 FROM table WHERE table.classified_id = $classified_id Wont the last one only select 1 record, which is exactly what I need, so that it doesn't have to scan the entire table but instead stops searching for records after 1 is found? Or am I dreaming this? Thanks

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  • making an SQL date column visible to a Drupal view

    - by Donal
    I'm trying to make a table visible to Views. One of the columns has type date (as opposed to a Unix timestamp). The example I initially tried to copy from is in modules/comment.views.inc in the Views module: // timestamp (when comment was posted) $data['comments']['timestamp'] = array( 'title' => t('Post date'), 'help' => t('Date and time of when the comment was posted.'), 'field' => array( 'handler' => 'views_handler_field_date', 'click sortable' => TRUE, ), 'sort' => array( 'handler' => 'views_handler_sort_date', ), 'filter' => array( 'handler' => 'views_handler_filter_date', ), ); This makes the dates, which are all in the past year or so, show up as "1 Jan 1970 00:33", so evidently a value of '2010-05-12', for example, is being interpreted as 2010 seconds past 1 Jan 1970 00:00. Can anyone point me to a correct way of exporting date columns? EDIT: I'm following up on some clues found at http://drupal.org/node/476774 .

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  • how do I integrate the aspnet_users table that comes with asp.net membership into my existing databa

    - by ooo
    i have a database that already has a users table COLUMNS: userID - int loginName - string First - string Last - string i just installed the asp.net membership table. Right now all of my tables are joined into my users table foreign keyed into the "userId" field How do i integrate asp.net_users table into my schema? here are the ideas i thought of: Add a membership_id field to my users table and on new inserts, include that new field in my users table. This seems like the cleanest way as i dont need to break any existing relationships. break all existing relationship and move all of the fields in my user table into the asp.net_users table. This seems like a pain but ultimately will lead to the most simple, normalized solution any thoughts?

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  • Do I need to drop index on temp table?

    - by Phil
    Hi, Fairly simple question, but I don't see it anywhere else on SO: Do indexes (indices?) on a temporary table get automatically deleted with the temporary table? I'd imagine they do but I don't really know how to check to make sure. Thanks, Phil

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  • performance issue: difference between select s.* vs select *

    - by kamil
    Recently I had some problem in performance of my query. The thing is described here: poor Hibernate select performance comparing to running directly - how debug? After long time of struggling, I've finally discovered that the query with select prefix like: select sth.* from Something as sth... Is 300x times slower then query started this way: select * from Something as sth.. Could somebody help me, and asnwer why is that so? Some external documents on this would be really useful. The table used for testing was: SALES_UNIT table contains some basic info abot sales unit node such as name and etc. The only association is to table SALES_UNIT_TYPE, as ManyToOne. The primary key is ID and field VALID_FROM_DTTM which is date. SALES_UNIT_RELATION contains relation PARENT-CHILD between sales unit nodes. Consists of SALES_UNIT_PARENT_ID, SALES_UNIT_CHILD_ID and VALID_TO_DTTM/VALID_FROM_DTTM. No association with any tables. The PK here is ..PARENT_ID, ..CHILD_ID and VALID_FROM_DTTM The actual query I've done was: select s.* from sales_unit s left join sales_unit_relation r on (s.sales_unit_id = r.sales_unit_child_id) where r.sales_unit_child_id is null select * from sales_unit s left join sales_unit_relation r on (s.sales_unit_id = r.sales_unit_child_id) where r.sales_unit_child_id is null Same query, both uses left join and only difference is with select.

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  • Help me choose between XML or SQL Lite on android

    - by Ngetha
    I have an android app that periodically, say once a week downloads content from a server in XML. The content is used by the app, different Acitivities use different parts of the content. My question is a design one, should I save the data in SQlite or just keep it as an XML file, which one would be faster to read? The app can only use one content piece at a time, which means subsequent XML content downloads replace the old one.

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  • multi-row update table with "different" data

    - by kralco626
    I think the best way to explain this is to tell you what I have. I have two tables A and B both have columns Field1 and Field2. However Field 2 is not populated in table B I want to populate field 2 of table B with field 2 of table A where field 1 of table A matches field 1 of table B. something like update tableB set Field2 = tableA.field2 where tablea.field1 = tableb.field1. The reason this may seem so odd and obscure is that I'm tyring to do an inital data load form an old database to a new one. please let me know if you need clarification

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  • How can I use an array within a SQL query

    - by ThinkingInBits
    So I'm trying to take a search string (could be any number of words) and turn each value into a list to use in the following IN statement) in addition, I need a count of all these values to use with my having count filter $search_array = explode(" ",$this->search_string); $tag_count = count($search_array); $db = Connect::connect(); $query = "select p.id from photographs p left join photograph_tags c on p.id = c.photograph_id and c.value IN ($search_array) group by p.id having count(c.value) >= $tag_count"; This currently returns no results, any ideas?

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  • MySQL "NULL" questions

    - by Camran
    I have a table with several columns. Sometimes some of these column fields may be empty (ie. I won't use them in some cases). My questions: Would it be smart to set them to NULL in phpmyadmin? What does the "NULL" property actually do? Would I gain anything at all by setting them to NULL? Is it possible to use a NULL field the same way even though it is set to null?

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  • Update table with if statement PS/SQL

    - by Matt
    I am trying to do something like this but am having trouble putting it into oracle coding. BEGIN IF ((SELECT complete_date FROM task_table WHERE task_id = 1) IS NULL) THEN UPDATE task_table SET complete_date = //somedate WHERE task_id = 1; ELSE UPDATE task_table SET complete_date = NULL; END IF; END; But this does not work i also tried IF EXISTS(SELECT complete_date FROM task_table WHERE task_id = 1) with no luck

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  • MSSQL Sum query

    - by ldb
    today my problem is this i have 2 column and i wish check if the sum of that columns isn't Higher then a value(485 for example) and if is do a query...i though to do SELECT * FROM table WHERE ColumnA+ColumnB<485 But isn't working... i've already tried with SELECT Sum(ColumnA)+Sum(ColumnB) AS Total FROM table but it gives me 1 column with the sum of all rows, i instead want a row for every sum. so how can i do..? xD i hope you understood if not just ask that i try to explain it better! and thanks in advice for who want to help me! EDIT: I Found out XD the problem was that the columns was Smallint and the result of 1 or more rows was more than 32k so it wasn't working! Thanks At all!!

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  • SSAS OLAP MDX and relationships

    - by Sonic Soul
    I new to OLAP, and still not sure how to create a relationship between 2 or more entities. I am basing my cube on views. For simplicity sake let's call them like this: viewParent (ParentID PK) viewChild (ChildID PK, ParentID FK) these views have more fields, but they're not important for this question. in my data source, i defined a relationship between viewParent and viewChild using ParentID for the link. As for measures, i was forced to create separate measures for Parent and Child. in my MDX query however, the relationship does not seem to be enforced. If i select record count for parent, child, and add some filters for the parent, the child count is not reflecting it.. SELECT { [Measures].[ParentCount],[Measures].[ChildCount] } ON COLUMNS FROM [Cube] WHERE { ( {[Time].[Month].&[2011-06-01T00:00:00]} ,{[SomeDimension].&[Foo]} ) } the selected ParentCount is correct, but ChildCount is not affected by any of the filters (because they are parent filters). However, since i defined a relationship, how can i take advantage of that to filter children by parent filter?

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  • History tables pros, cons and gotchas - using triggers, sproc or at application level.

    - by Nathan W
    I am currently playing around with the idea of having history tables for some of my tables in my database. Basically I have the main table and a copy of that table with a modified date and an action column to store what action was preformed eg Update,Delete and Insert. So far I can think of three different places that you can do the history table work. Triggers on the main table for update, insert and delete. (Database) Stored procedures. (Database) Application layer. (Application) My main question is, what are the pros, cons and gotchas of doing the work in each of these layers. One advantage I can think of by using the triggers way is that integrity is always maintained no matter what program is implmentated on top of the database.

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  • Getting the last element of a Postgres array, declaratively

    - by Wojciech Kaczmarek
    How to obtain the last element of the array in Postgres? I need to do it declaratively as I want to use it as a ORDER BY criteria. I wouldn't want to create a special PGSQL function for it, the less changes to the database the better in this case. In fact, what I want to do is to sort by the last word of a specific column containing multiple words. Changing the model is not an option here. In other words, I want to push Ruby's sort_by {|x| x.split[-1]} into the database level. I can split a value into array of words with Postgres string_to_array or regexp_split_to_array functions, then how to get its last element?

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  • Query crashes MS Access

    - by user284651
    THE TASK: I am in the process of migrating a DB from MS Access to Maximizer. In order to do this I must take 64 tables in MS ACCESS and merge them into one. The output must be in the form of a TAB or CSV file. Which will then be imported into Maximizer. THE PROBLEM: Access is unable to perform a query that is so complex it seems, as it crashes any time I run the query. ALTERNATIVES: I have thought about a few alternatives, and would like to do the least time-consuming one, out of these, while also taking advantage of any opportunities to learn something new. Export each table into CSVs and import into SQLight and then make a query with it to do the same as what ACCESS fails to do (merge 64 tables). Export each table into CSVs and write a script to access each one and merge the CSVs into a single CSV. Somehow connect to the MS ACCESS DB (API), and write a script to pull data from each table and merge them into a CSV file. QUESTION: What do you recommend?

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  • How do I all the registered users on a day report

    - by Nadal
    I have a table called users where I have two columns: name and created_at. created_at column column is of type datetime and it stores the datetime when this user was created. I need to know the number of users created for a given date range. Let's say I ask give me user report between 1-nov-2010 and 30-nov-2010 . I need something like this 1-nov-2010: 2 2-nov-2010: 5 The problem I am running into is that created_at data has value upto second. How do I check if a created_at date falls within a given date. Any help in solving this problem is appreciated. I am using mysql5.

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