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• Row selection based on subtable data in MySQL

  - by Felthragar

  I've been struggling with this selection for a while now, I've been searching around StackOverflow and tried a bunch of stuff but nothing that helps me with my particular issue. Maybe I'm just missing something obvious. I have two tables: Measurements, MeasurementFlags "Measurements" contain measurements from a device, and each measurement can have properties/attributes attached to them (commonly known as "flags") to signify that the measurement in question is special in some way or another (for instance, one flag may signify a test or calibration measurement). Note: One record per flag! Right, so a record from the "Measurements" table can theoreticly have an unlimited amount of MeasurementFlags attached to it, or it can have none. Now, I need to select records from "Measurements", that have an attached "MeasurementFlag" valued "X", but it must also NOT have a flag valued "Y" attached to it. We're talking about a fairly large database with hundreds of millions of rows, which is why I'm trying to keep all of this logic within one query. Splitting it up would create too many queries, however if it's not possible to do in one query I guess I don't have a choise. Thanks in advance.

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• MySQL - Select all as one string

  - by poru

  How could I select all as one string seperated with a ,? Example table: Table Stringtest Examplestring2 Anotherstring Otherstring And the selected result should be Stringtest,Examplestring2,Anotherstring,Otherstring.

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• compare string to date on mysql

  - by Mercer

  hello, i have a table with a date, this date is a string i want to compare this string with a date in my request. SELECT FE_CLIENT.* FROM FE_CLIENT WHERE D_DATFINPUBLI < '2010/06/03' How can i cast my column date_deb to a date for compare ..?

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• What is an index in MySQL?

  - by Eric

  http://i.imgur.com/JdsUK.jpg I created a table like the picture above. What are the "Indexes"? primary key? unique? It works well without setting indexes.. What do they do? why do I need them? Also, I set all String fields to TEXT because I didn't know how many characters I need. Is this a good idea? I don't see any difference. Thanks!

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• Storing connections between people in a MySql database

  - by daniel

  I would like to create a database where I store the links between people. I then need to bring back the records detailing which people are connected to which others. I need to output: person1 is connected to person2 is connected with person3 etc. How can I get started with this task?

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• Mysql query for finding 10 close marks of class

  - by sharma

  I want nearest 10 marks for particular student. For example John has marks 73 then i have to find 10 student with marks greater than 73 in ascending order nearest to John. My Table structure is (id,name,marks).

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• Mysql Database Question about Large Columns

  - by murat

  Hi, I have a table that has 100.000 rows, and soon it will be doubled. The size of the database is currently 5 gb and most of them goes to one particular column, which is a text column for PDF files. We expect to have 20-30 GB or maybe 50 gb database after couple of month and this system will be used frequently. I have couple of questions regarding with this setup 1-) We are using innodb on every table, including users table etc. Is it better to use myisam on this table, where we store text version of the PDF files? (from memory usage /performance perspective) 2-) We use Sphinx for searching, however the data must be retrieved for highlighting. Highlighting is done via sphinx API but still we need to retrieve 10 rows in order to send it to Sphinx again. This 10 rows may allocate 50 mb memory, which is quite large. So I am planning to split these PDF files into chunks of 5 pages in the database, so these 100.000 rows will be around 3-4 million rows and couple of month later, instead of having 300.000-350.000 rows, we'll have 10 million rows to store text version of these PDF files. However, we will retrieve less pages, so again instead of retrieving 400 pages to send Sphinx for highlighting, we can retrieve 5 pages and it will have a big impact on the performance. Currently, when we search a term and retrieve PDF files that have more than 100 pages, the execution time is 0.3-0.35 seconds, however if we retrieve PDF files that have less than 5 pages, the execution time reduces to 0.06 seconds, and it also uses less memory. Do you think, this is a good trade-off? We will have million of rows instead of having 100k-200k rows but it will save memory and improve the performance. Is it a good approach to solve this problem and do you have any ideas how to overcome this problem? The text version of the data is used only for indexing and highlighting. So, we are very flexible. Thanks,

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• mysql to get depth of record, count parent and ancestor records

  - by Nate

  Hey All, Say I have a post table containing the fields post_id and parent_post_id. I want to return every record in the post table with a count of the "depth" of the post. By depth, I mean, how many parent and ancestor records exist. Take this data for example... post_id parent_post_id ------- -------------- 1 null 2 1 3 1 4 2 5 4 The data represents this hierarchy... 1 |_ 2 | |_ 4 | |_ 5 |_ 3 The result of the query should be... post_id depth ------- ----- 1 0 2 1 3 1 4 2 5 3 Thanks in advance!

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• Deleting Duplicates in MySQL

  - by elmaso

  Query was this: CREATE TABLE `query` ( `id` int(11) NOT NULL auto_increment, `searchquery` varchar(255) NOT NULL default '', `datetime` int(11) NOT NULL default '0', PRIMARY KEY (`id`) ) ENGINE=MyISAM first I want to drop the table with: ALTER TABLE `querynew` DROP `id` and then delete the double entries.. I tried it with: INSERT INTO `querynew` SELECT DISTINCT * FROM `query` but with no success.. :( and with ALTER TABLE query ADD UNIQUE ( searchquery ) - is it possible to save the queries only one time?

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• De-normalization alternative to specific MYSQL problem?

  - by Booker

  I am facing quite a specific optimization problem. I currently have 4 normalized tables of data. Every second, possibly thousands of users will pull down up-to-date info from these tables using AJAX. The thing is that I can predict relatively easily which subset of data they need... The most recent 100 or so entries in those 4 normalized tables. I have been researching de-normalization... but feel that perhaps there is an easier solution. I was thinking that I could somehow every second run one sql query to condense the needed info, store it in a temp cached table and then have all of the user queries just draw from this. This will allow the complex join of 4 tables to only be run once, and then from there the users just need to do a simple lookup from the cached table. I really don't know if this is feasible. Comments on this or any other suggestions would be much appreciated. Thanks!

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• Troubleshoot MySQL query

  - by Victor

  I need help with this code, it doesent insert the values to my database. Probably a simple problem but it's late here in Sweden so i would appriciate if someone could have a look at this and tell me what's wrong: include "../../inc/mysql_config.php"; $to = mysql_real_escape_string($_POST['to']); $message = mysql_real_escape_string($_POST['message']); mysql_query("INSERT INTO messages (to, message) VALUES ('".$to."', '".$message."')"); Every variable have an value, double checked that and the mysql_config.php is working.

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• How to load the rest of the data in mysql in php

  - by user225269

  I have trouble figuring out how do I load the rest of the data in html. Here is my code: <?php $con = mysql_connect("localhost","root","nitoryolai123$%^"); if (!$con) { die('Could not connect: ' . mysql_error()); } mysql_select_db("school", $con); $result = mysql_query("SELECT * FROM student WHERE IDNO='$_GET['id']'"); ?> <?php while ( $row = mysql_fetch_array($result) ) { ?> <table class="a" border="0" align="center" cellpadding="0" cellspacing="1" bgcolor="#D3D3D3"> <tr> <form name="formcheck" method="post" action="updateact.php" onsubmit="return formCheck(this);"> <td> <table border="0" cellpadding="3" cellspacing="1" bgcolor=""> <tr> <td colspan="16" height="25" style="background:#5C915C; color:white; border:white 1px solid; text-align: left"><strong><font size="2">Update Students</td> <tr> <td width="30" height="35"><font size="2">*I D Number:</td> <td width="30"><input name="idnum" onkeypress="return isNumberKey(event)" type="text" maxlength="5" id='numbers'/ value="<?php echo $_GET['id']; ?>"></td> </tr> <tr> <td width="30" height="35"><font size="2">*Year:</td> <td width="30"><input name="yr" onkeypress="return isNumberKey(event)" type="text" maxlength="5" id='numbers'/ value="<?php echo $row["YEAR"]; ?>"></td> this is the part where I am getting the error: mysql_select_db("school", $con); $result = mysql_query("SELECT * FROM student WHERE IDNO='$_GET['id']'"); ? What do you recommend that I could do so that I can also load the ID Numbers corresponding data into the other forms?

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• MySQL query killing my server

  - by Webnet

  Looking at this query there's got to be something bogging it down that I'm not noticing. I ran it for 7 minutes and it only updated 2 rows. //set product count for makes $tru->query->run(array( 'name' => 'get-make-list', 'sql' => 'SELECT id, name FROM vehicle_make', 'connection' => 'core' )); while($tempMake = $tru->query->getArray('get-make-list')) { $tru->query->run(array( 'name' => 'update-product-count', 'sql' => 'UPDATE vehicle_make SET product_count = ( SELECT COUNT(product_id) FROM taxonomy_master WHERE v_id IN ( SELECT id FROM vehicle_catalog WHERE make_id = '.$tempMake['id'].' ) ) WHERE id = '.$tempMake['id'], 'connection' => 'core' )); } I'm sure this query can be optimized to perform better, but I can't think of how to do it. vehicle_make = 45 rows taxonomy_master = 11,223 rows vehicle_catalog = 5,108 rows All tables have appropriate indexes

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• How to model parent to child pair in MySQL (SQL)

  - by mikeschuld

  I have a data model that includes element types Stage, Actor, and Form. Logically, Stages can be assigned pairs of ( Form <--- Actor ) which can be duplicated many times (i.e. same person and same form added to the same stage at a later date/time). Right now I am modeling this with these tables: Stage Form Actor Form_Actor _______________ |Id | |FormId | --> Id in Form |ActorId | --> Id in Actor Stage_FormActor __________________ |Id | |StageId | --> Id in Stage |FormActorId | --> Id in Form_Actor I am using CodeSmith to generate the data layer for this setup and none of the templates really know how to handle this type of relationship correctly when generating classes. Ideally, the ORM would have Stage.FormActors where FormActor would be the pair Form, Actor. Is this the correct way to model these relationships. I have tried using all three Ids in one table as well Stage_Form_Actor ______________ |Id | |StageId | --> Id in Stage |FormId | --> Id in Form |ActorId | --> Id in Actor This doesn't really get generated very well either. Ideas?

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• MySQL Insert not working with Date column

  - by Ian McCullough

  Hello All, I am having an issue with a simple insert query into a table. I have this PHP Code $T_MEMBER = "INSERT INTO T_MEMBER (MEMBER_IDENTIFIER,LAST_NAME,FIRST_NAME,BIRTH_DATE) VALUES ('$memberID','$last','$first','$birthdate')"; mysql_query($T_MEMBER) or die(mysql_error()); Here are a few examples of what the query looks like if i echo it: INSERT INTO T_MEMBER (MEMBER_IDENTIFIER,LAST_NAME,FIRST_NAME,BIRTH_DATE) VALUES ('2007','Hayes','Karin','1958-30-10') INSERT INTO T_MEMBER (MEMBER_IDENTIFIER,LAST_NAME,FIRST_NAME,BIRTH_DATE) VALUES ('2020','Long','Peggy','1968-29-5') INSERT INTO T_MEMBER (MEMBER_IDENTIFIER,LAST_NAME,FIRST_NAME,BIRTH_DATE) VALUES ('2021','Torres','Diane','1968-30-8') BIRTH_DATE is a date type column. The problem is, after i do any of these queries, the date shows up as 000-00-00!!!! I have been wracking my brain and i cannot seem to find the issue. Thanks, Ian

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• adding DATE_SUB to query to return range of values in mysql

  - by ian

  Here is my original query: $query = mysql_query("SELECT s.*, UNIX_TIMESTAMP(`date`) AS `date`, f.userid as favoritehash FROM songs s LEFT JOIN favorites f ON f.favorite = s.id AND f.userid = '$userhash' ORDER BY s.date DESC"); This returns all the songs in my DB and then joins data from my favorites table so I can display wich items a return visitors has clicked as favorites or not. Visitors are recognized by a unique has storred in a cookie and in the favorites table. I need to alter this query so that I can get just the last months worth of songs. Below is my attempt at adding DATE_SUB to my query: $query = mysql_query("SELECT s.*, UNIX_TIMESTAMP(`date`) AS `date`, f.userid as favoritehash FROM songs s WHERE `date` >= DATE_SUB( NOW( ) , INTERVAL 1 MONTH ) LEFT JOIN favorites f ON f.favorite = s.id AND f.userid = '$userhash' ORDER BY s.date DESC"); Suggestions?

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• auto_increment in MySQL - can I omit it?

  - by kees-kist

  I've noticed that PHPmyAdmin creates the following SQL for table creation: CREATE TABLE something ( ... ) auto_increment=1; When I write a database creation script I don't use the auto_increment bit. From reading related questions here I understand that it determines the starting value for auto_increment values. But it is good practice to reset it to 1, or should I just leave it out of the SQL so that the default is used?

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• MySQL get data from another table with duplicate ID/data

  - by steamboy

  How to query data from table_1 which ID is not available on table_2 that has duplicate ID's. See example below. I want to get ID 5 and 6 of Table 1 from Table 2 **Table 1** ID Name 1 a 2 b 3 c 4 d 5 e 6 f **Table 2** Table 1 ID 1 1 2 2 2 3 4 Thanks!

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• Select nth percentile from MySQL

  - by mazin k.

  I have a simple table of data, and I'd like to select the row that's at about the 40th percentile from the query. I can do this right now by first querying to find the number of rows and then running another query that sorts and selects the nth row: select count(*) as `total` from mydata; select * from mydata order by `field` asc limit 37,1; Can I combine these two queries into a single query?

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• Get list of duplicate rows in MySql

  - by user347033

  Hi, i have a table like this ID nachname vorname 1 john doe 2 john doe 3 jim doe 4 Michael Knight I need a query that will return all the fields (select *) from the records that have the same nachname and vorname (in this case, records 1 and 2). Can anyone help me with this? Thanks

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• Return order of MySQL SHOW COLUMNS

  - by rich

  Hey guys. Simple one this, but one I can't seem to find any information on so here goes. I need to find the columns in a specific table, which is no problem.... SHOW COLUMNS FROM tablename LIKE '%ColumnPrefix%'; But I need to know what order they will be returned, preferable by choosing to order the results ascending alphabetically. I have had no luck with using ORDER BY Field. Any ideas? Cheers!

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• mysql - speedup regex

  - by Uwe

  I have a table: +--------+------------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +--------+------------------+------+-----+---------+----------------+ | idurl | int(11) | NO | PRI | NULL | auto_increment | | idsite | int(10) unsigned | NO | MUL | NULL | | | url | varchar(2048) | NO | | NULL | | +--------+------------------+------+-----+---------+----------------+ the select statement is: SELECT idurl, url FROM URL WHERE idsite = 34 AND url REGEXP '^https\\://www\\.domain\\.com/checkout/step_one\\.php.*' The query needs 5 seconds on a table with 1000000 rows. Can I achieve a speedup with indexes or something else?

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• MySQL JDBC date issues with database server in different timezone

  - by Somatik

  I have a database server in "Europe/London" time zone and my web server in "Europe/Brussels". Since it is summer time now my application server has a 2 hour difference. I created a test to reproduce my issue: Query q = JPA.em().createNativeQuery("SELECT UNIX_TIMESTAMP(startDateTime) FROM `Event` WHERE `id` =574"); BigInteger unix = (BigInteger) q.getSingleResult(); System.out.println(unix + "000 UNIX_TIMESTAMP to BigInteger"); Query q2 = JPA.em().createNativeQuery("SELECT startDateTime FROM `Event` WHERE `id` =574"); Timestamp o = (Timestamp) q2.getSingleResult(); System.out.println(o.getTime() + " Timestamp"); The startDateTime column is defined as 'datetime' (but same issue with 'timestamp') The output I am getting is this: 1340291591000 UNIX_TIMESTAMP to BigInteger 1340284391000 Timestamp Reading java date objects results in a shift in time zone, how do I fix this? I would expect the jdbc driver to just set the "unix time" value it gets from the server in the Date object. (a proper solution should work with any timezone combination, not only for db in GMT)

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• mysql 2 primary key onone table

  - by Bharanikumar

  CREATE TABLE Orders -> ( -> ID SMALLINT UNSIGNED NOT NULL, -> ModelID SMALLINT UNSIGNED NOT NULL, -> Descrip VARCHAR(40), -> PRIMARY KEY (ID, ModelID) -> ); Basically May i know ... Shall we create the two primary key on one table... Is it correct... Bcoz as per sql law,,, We can create N number of unque key in one table, and only one primary key only is the LAW know... Then how can my system allowing to create multiple primary key ? Please advise .... what is the general rule

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• Database design MySQL using foreign keys

  - by dscher

  I'm having some a little trouble understanding how to handle the database end of a program I'm making. I'm using an ORM in Kohana, but am hoping that a generalized understanding of how to solve this issue will lead me to an answer with the ORM. I'm writing a program for users to manage their stock research information. My tables are basically like so: CREATE TABLE tags( id INT AUTO_INCREMENT NOT NULL PRIMARY KEY, tags VARCHAR(30), UNIQUE(tags) ) ENGINE=INNODB DEFAULT CHARSET=utf8; CREATE TABLE stock_tags( id INT AUTO_INCREMENT NOT NULL PRIMARY KEY, tag_id INT NOT NULL, stock_id INT NOT NULL, FOREIGN KEY (tag_id) REFERENCES tags(id), FOREIGN KEY(stock_id) REFERENCES stocks(id) ON DELETE CASCADE ) ENGINE=INNODB DEFAULT CHARSET=utf8; CREATE TABLE notes( id INT AUTO_INCREMENT NOT NULL, stock_id INT NOT NULL, notes TEXT NOT NULL, FOREIGN KEY (stock_id) REFERENCES stocks(id) ON DELETE CASCADE, PRIMARY KEY(id) ) ENGINE=INNODB DEFAULT CHARSET=utf8; CREATE TABLE links( id INT AUTO_INCREMENT NOT NULL, stock_id INT NOT NULL, links VARCHAR(2083) NOT NULL, FOREIGN KEY (stock_id) REFERENCES stocks(id) ON DELETE CASCADE, PRIMARY KEY(id) ) ENGINE=INNODB DEFAULT CHARSET=utf8; How would I get all the attributes of a single stock, including its links, notes, and tags? Do I have to add links, notes, and tags columns to the stocks table and then how do you call it? I know this differs using an ORM and I'd assume that I can use join tables in SQL. Thanks for any help, this will really help me understand the issue a lot better.

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