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  • MySQL - are FK's useful / viable in a web app?

    - by yoda
    Hi all, I've encountered this discussion related to FK's and web applications. Basically some people say that FK's in web applications doesn't represent a real improvement and can even make the application slower in some cases. What do you guys think, what's your experience? -- A quote from Heikki Tuuri, creator of InnoDB engine, founder and CEO of Innobase: InnoDB checks foreign keys as soon as a row is updated, no batching is performed or checks delayed till transaction commit Foreign keys are often serious performance overhead, but help maintain data consistency Foreign Keys increase amount of row level locking done and can make it spread to a lot of tables besides the ones directly updated

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  • How to order the images in a mysql database?

    - by user305270
    Hy! Here is my problem: i have a profile and this profile has for example 100 images. When someone visit this profile the first image will be the first result of my query that sorts by updated_at. But if the user would want to put the image with the (id = 8) to be the first, then (id = 22) then (id = 88) and so on? I need to put another field or is really necessary a new table to make a custom sort on images? and maybe someone explain this to me how to do? thanks, i appreciate your help ;)

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  • MySQL, how can I SELECT WHERE one field value doesn't occurs in another?

    - by Jules
    I'm trying to do a search on my test server, speed isn't so important. I want to find if a phrase, the whole contents of one field, occurs in any part (as a whole) doesn't occur in another field. Heres my current query which finds if the phrase does occur SELECT pads.padid, pads.programname, keywords.word FROM Pads JOIN keywords ON Pads.Padid = keywords.Padid WHERE pads.Programname = keywords.word AND RemoveMeDate = '2001-01-01 00:00:00' My problem is that the field word contains other words too. I need to produce a count of where there isn't a keywords record with keywords.word equal to pads.programname ? EDIT: So if I have these records Pads: PadID=3 ProgramName=my prog PadID=4 ProgramName=Bad prog PadID=5 ProgramName=Good prog PadID=6 ProgramName=other prog Keywords: PadID=3 word=fox prog PadID=3 word=pig prog PadID=4 word=big prog PadID=4 word=nice prog PadID=5 word=fox prog PadID=6 word=bad prog PadID=6 word=fox prog The query I want would retun a count of 3 and record 6 has bad prog

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  • Failed to obtain JDBC Driver for MySQL under Tomcat environment

    - by Michael Mao
    Hi all: I've been trying to obtain the Driver class for JDBC connection to MySQL. The workstation is running on Linux, Fedora 10. I have manually set up the classpath variable for Java by CLI like this: bash-3.2$ echo $CLASSPATH /home/cmao/public_html/jsp/mysql-connector-java-5.1.12-bin.jar This shows that I've added the lastest mysql connection jar archive to my CLASSPATH variable. I've created a test JSP page which can be found here And source code for this page is: <%@page language="java"%> <%@page import="java.sql.*"%> <%@page import="java.util.*"%> <html> <head> <title>UTS JDBC MySQL connection test page</title> </head> <body> <% Connection con = null; out.print("Java version is : " + System.getProperty("java.version") + "<br />"); out.print("Tomcat version is : " + application.getServerInfo() + "<br />"); out.print("Servlet version is: " + application.getMajorVersion() + "<br />"); out.print("JSP version is : " + JspFactory.getDefaultFactory().getEngineInfo().getSpecificationVersion() +"<br />"); //out.print("Java classpath is : " + System.getProperty("java.class.path")+ "<br />"); //out.print("JSP classpath is : " + appliaction.getAttribute("org.apache.catalina.jsp_classpath") + "<br />"); //out.print("Tomcat classpath is : " + System.getProperty("org.apache.tomcat.common.classpath") + "<br />"); try { Class c = Class.forName("com.mysql.jdbc.Driver"); } catch(Exception e) { out.println("Error! Failed to obtain JDBC driver for MySQL... Missing class \"com.mysql.jdbc.Driver\"<br />"); } %> </body> </html> None of those commented out line would work, various Jsper Expetions would be thrown. You can check those Error pages from the following links: classpath Error page catalina Error page tomcat Error page It seems, from my limited knowledge of JSP and Servlet, the Tomcat environment "ignores" my Java CLASSPATH? In which case I cannot configure the MySQL JDBC package to let my Servlets(a JSP is but a Servlet anyway) work. I am not sure how to fix this issue. would it be better if I use an IDE like Eclipse or NetBeans and create a real Java "web app" so that everything can be "self-configured" by the usage of a web.config XML configuration file? So that I can certainly bypass this Tomcat environment restriction? Many thanks for the suggestions in advance.

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  • Whats the most efficient MySQL column types for this data?

    - by AlabamaKush
    I have several tables with some pretty standard data in each. Can somebody help me optimize them by telling me the best column types for this data. Whats beside them is what I have currently. Number (max length 7) --> MEDIUMINT(8) Unsigned Text (max length 30) --> VARCHAR(30) Text (max length 200) --> VARCHAR(200) Number (max length 4) --> SMALLINT(5) Unsigned Number (either 0 or 1) --> TINYINT(1) Unsigned Text (max length 500) --> TEXT Any suggestions? I'm just guessing with this so I know some of them are wrong...

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  • How to Display result of subquery rows as one column in MySQL?

    - by SIA
    Hi I have three tables Category, Movies and RelCatMov Category-table categoryid, categoryName 1 thriller 2 supsense 3 romantic 4 action 5 sci-fi Movies-table movieid, movieName 1 Avataar 2 Titanic 3 NinjaAssassin RelCatMov-table categoryid, MovieID 1 1 2 2 3 2 4 2 5 2 Now i Want to display a the record as MovieName Categories Titanic Suspense,Romantic,Sci-fi,action How to do this. I am writing a query select MovieName,(select categoryname from category b,relcatmov c where b.categoryid=c.categoryid and c.movieid=a.movieid) as categories from movies a; Error: Subquery returns more than one row!!! How to display the result of rows in one column? Please help!!!

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  • Is there a good way to execute MySQL statements atomically via JDBC?

    - by javanix
    Suppose I have a table that contains valid data. I would like to modify this data in some way, but I'd like to make sure that if any errors occur with the modification, the table isn't changed and the method returns something to that effect. For instance, (this is kind of a dumb example, but it illustrates the point so bear with me) suppose I want to edit all the entries in a "name" column so that they are properly capitalized. For some reason, I want either ALL of the names to have proper capitalization, or NONE of them to have proper capitalization (and the starting state of the table is that NONE of them do). Is there an already-implemented way to run a batch update on the table and be assured that, if any one of the updates fails, all changes are rolled back and the table remains unchanged? I can think of a few ways to do this by hand (though suggestions are welcomed), but it'd be nice if there was some method I could use that would function this way. I looked at the java.sql.statement.executeBatch() command, but I'm not convinced by the documentation that my table wouldn't be changed if it failed in some manner.

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  • PHP / MYSQL: Database empties when I use a variable in the WHERE condition of the last mysql_query

    - by Christian Cugnet
    <?php require 'connect.php'; $search = $_POST["search"]; These two queries work fine. So I used their format for the one below. $result = mysql_query("SELECT * FROM `subjects` WHERE $search = `student_id`"); $result2 = mysql_query("SELECT * FROM `grades` WHERE $search = `student_id`"); while($row = mysql_fetch_array($result)) { $row2 = mysql_fetch_array($result2); echo"<table border='1'>"; echo "<tr>"; echo "<th>Subjects:</th>"; echo "<th>Current Mark:</th>"; echo "<th>Edit Mark:</th>"; echo"</tr>"; echo"<tr>"; echo "<td>". $row['c1'] ."</td>"; echo "<td>". $row2['m1'] ."</td>"; echo "<td><input type='text' name='m1'></td>"; echo "</tr>"; echo "<tr>"; echo "<td>". $row['c2'] ."</td>"; echo "<td>". $row2['m2'] ."</td>"; echo "<td><input type='text' name='m2'></td>"; echo "</tr>"; echo "<tr>"; echo "<td>". $row['c3'] ."</td>"; echo "<td>". $row2['m3'] ."</td>"; echo "<td><input type='text' name='m3'></td>"; echo "</tr>"; echo "<tr>"; echo "<td>". $row['c4'] ."</td>"; echo "<td>". $row2['m4'] ."</td>"; echo "<td><input type='text' name='m4'></td>"; echo "</tr>"; echo "<tr>"; echo "<td>". $row['c5'] ."</td>"; echo "<td>". $row2['m5'] ."</td>"; echo "<td><input type='text' name='m5'></td>"; echo "</tr>"; echo "<tr>"; echo "<td>". $row['c6'] ."</td>"; echo "<td>". $row2['m6'] ."</td>"; echo "<td><input type='text' name='m6'></td>"; echo "</tr>"; echo "<tr>"; echo "<td>". $row['c7'] ."</td>"; echo "<td>". $row2['m7'] ."</td>"; echo "<td><input type='text' name='m7'></td>"; echo "</tr>"; echo "</table>"; echo "<input type='submit' name='submit' value='Submit'>"; echo "</form>"; } $M1 = $_POST["m1"]; $M2 = $_POST["m2"]; $M3 = $_POST["m3"]; $M4 = $_POST["m4"]; $M5 = $_POST["m5"]; $M6 = $_POST["m6"]; $M7 = $_POST["m7"]; It works if I put numbers e.x. 11111 Otherwise it just enters blank spaces into the table. I've tried '".$search."' I've tried ".$search." mysql_query("UPDATE grades SET m1 = '$M1', m2 = '$M2',m3 = '$M3',m4 = '$M4',m5 = '$M5',m6 = '$M6',m7 = '$M7' WHERE $search = `student_id`"); ?> Table +------------+---+---+---+---+---+---+---+ |student_id|m1|m2|m3|m4|m5|m6|m7| +------------+---+---+---+---+---+---+---+ ===Database d1 == Table structure for table grades |------ |Column|Type|Null|Default |------ |//student_id//|int(5)|No| |m1|text|No| |m2|text|No| |m3|text|No| |m4|text|No| |m5|text|No| |m6|text|No| |m7|text|No| == Dumping data for table grades |11111| | | | | | | |11112|fg|fd|f|f|fd|f|f ===Database d1 == Table structure for table subjects |------ |Column|Type|Null|Default |------ |//student_id//|int(11)|No| |c1|text|No| |c2|text|No| |c3|text|No| |c4|text|No| |c5|text|No| |c6|text|No| |c7|text|No| == Dumping data for table subjects |11111|English|Math|Science|Sport|IT|Art|History |11112|grdgg|vsbvbbb|bdbbrfd|bdbrb|dbrbfbf|fbdfbdbf|dbfbdfb

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  • What's a reasonable number of rows and tables to be able to join in MySQL?

    - by Philip Brocoum
    I have one table that maps locations to postal codes. For example, New York State has about 2000 postal codes. I have another table that maps mail to the postal codes it was sent to, but this table has about 5 million rows. I want to find all the mail that was sent to New York State, which seems simple enough, but the query is unbelievably slow. I haven't been able to even wait long enough for it to finish. Is the problem that there are 5 million rows? I can't help but think that 5 million shouldn't be such a large number for a computer these days... Oh, and everything is indexed. Is SQL just not designed to handle such large joins?

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  • How do I bring forward the SELECTED option in PHP from MySQL?

    - by Derek
    Hi all, In my update form, I want the fields to recall the values that are already stored. This is very simple in a text field, but for my drop down () I'm having trouble with PHP reading the already stored name of user. Here is my query and code: $sql = "SELECT users.user_id, users.name FROM users"; $result = mysql_query($sql, $connection) or die ("Couldn't perform query $sql <br />".mysql_error()); $row = mysql_fetch_array($result);?> <label>Designated Person:</label> <select name="name" id="name"> <option value="<?php echo $row['user_id']?>" SELECTED><?php echo $row['name']?> - Current</option> <?php while($row = mysql_fetch_array($result)) { ?> <option value="<?php echo $row['user_id']; if (isset($_POST['user_id']));?>"><?php echo $row['fullname']?></option> <?php } ?> The result of this displays all of the users (as required) and lets me select a user then perform the change successfully...however the 'SELECTED' is always the first one in my database and never the user that was selected when my activity was added :( !!!

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  • PHP / MYSQL: Sanitizing user input - is this a bad idea?

    - by Greg
    I have one "go" script that fetches any other script requested and this is what I wrote to sanitize user input: foreach ($_REQUEST as $key => $value){ if (get_magic_quotes_gpc()) $_REQUEST[$key] = mysql_real_escape_string(stripslashes($value)); else $_REQUEST[$key] = mysql_real_escape_string($value); } I haven't seen anyone else use this approach. Is there any reason not to? EDIT - amended for to work for arrays: function mysql_escape($thing) { if (is_array($thing)) { $escaped = array(); foreach ($thing as $key => $value) { $escaped[$key] = mysql_escape($value); } return $escaped; } // else if (get_magic_quotes_gpc()) $thing = stripslashes($thing); return mysql_real_escape_string($thing); } foreach ($_REQUEST as $key => $value){ $_REQUEST[$key] = mysql_escape($value); }

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  • Safe to KILL a mysql process REPLACEing records in a large myisam table?

    - by threecheeseopera
    I have a REPLACE query running for a few days now on a few MyISAM tables, the largest having 20+million records. I need it to stop. It is, basically: REPLACE INTO really_large_table (a,b,c,d) SELECT e,f,g,h FROM big_table INNER JOIN huge_table ON big_table.x LIKE CONCAT('%', huge_table.y, '%'); I need to KILL it, and I am worried that I may corrupt really_large_table. Because the sub-query itself takes a significant amount of time, the REPLACEing probably occurs (relatively) infrequently; if this is true, does this make it less likely for the data to become corrupted? For the curious, here is the SO question asked about the query I am trying to kill.

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  • Mysql return value as 0 in the fetch result.

    - by Karthik
    I have this two tables, -- -- Table structure for table `t1` -- CREATE TABLE `t1` ( `pid` varchar(20) collate latin1_general_ci NOT NULL, `pname` varchar(20) collate latin1_general_ci NOT NULL ) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_general_ci; -- -- Dumping data for table `t1` -- INSERT INTO `t1` VALUES ('p1', 'pro1'); INSERT INTO `t1` VALUES ('p2', 'pro2'); -- -------------------------------------------------------- -- -- Table structure for table `t2` -- CREATE TABLE `t2` ( `pid` varchar(20) collate latin1_general_ci NOT NULL, `year` int(6) NOT NULL, `price` int(3) NOT NULL ) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_general_ci; -- -- Dumping data for table `t2` -- INSERT INTO `t2` VALUES ('p1', 2009, 50); INSERT INTO `t2` VALUES ('p1', 2010, 60); INSERT INTO `t2` VALUES ('p3', 2007, 200); INSERT INTO `t2` VALUES ('p4', 2008, 501); my query is, SELECT * FROM `t1` LEFT JOIN `t2` ON t1.pid = t2.pid Getting the result, pid pname pid year price p1 pro1 p1 2009 50 p1 pro1 p1 2010 60 p2 pro2 NULL NULL NULL My question is, i want to get the price value is 0 instead of NULL. How can i write the query to getting the price value is 0. Thanks in advance for help.

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  • mysql fetch result parent id and category id by single query?

    - by Karthik
    I have the table and values like this, CREATE TABLE `category` ( `id` INT( 4 ) NOT NULL AUTO_INCREMENT PRIMARY KEY , `category` VARCHAR( 50 ) NOT NULL , `parent` INT( 4 ) NOT NULL ) INSERT INTO `category` VALUES (1, 'MCA', 9); INSERT INTO `category` VALUES (2, 'M Tech', 9); INSERT INTO `category` VALUES (3, 'B Tech', 9); INSERT INTO `category` VALUES (4, 'BioTech', 9); INSERT INTO `category` VALUES (5, 'InfoTech', 9); INSERT INTO `category` VALUES (6, 'Chemical', 10); INSERT INTO `category` VALUES (7, 'Indus', 10); INSERT INTO `category` VALUES (8, 'Physics', 10); INSERT INTO `category` VALUES (9, 'Information Science', 0); INSERT INTO `category` VALUES (10, 'Others Science', 0); I need a single query for getting the values in terms of category and subcategory. 3rd values zero as category and others are subcategory.

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  • MySQL calling in Username to show instead of ID!

    - by Jess
    I have a users table, books table and authors table. An author can have many books, while a user can also have many books. (This is how my DB is currently setup). As I'm pretty new to So far my setup is like bookview.php?book_id=23 from accessing authors page, then seeing all books for the author. The single book's details are all displayed on this new page...I can get the output to display the user ID associated with the book, but not the user name, and this also applies for the author's name, I can the author ID to display, but not the name, so somewhere in the query below I am not calling in the correct values: SELECT users.user_id, authors.author_id, books.book_id, books.bookname, books.bookprice, books.bookplot FROM books INNER JOIN authors on books.book_id = authors.book_id INNER JOIN users ON books.book_id = users.user_id WHERE books.book_id=" . $book_id; Could someone help me correct this so I can display the author name and user name both associated with the book! Thanks for the help :)

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  • Removing "Using temporary; Using filesort" from this MySQL select+join+group by query

    - by claytontstanley
    I have the following query: select t.Chunk as LeftChunk, t.ChunkHash as LeftChunkHash, q.Chunk as RightChunk, q.ChunkHash as RightChunkHash, count(t.ChunkHash) as ChunkCount from chunksubset as t join chunksubset as q on t.ID = q.ID group by LeftChunkHash, RightChunkHash And the following explain table: id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE subsets ref PRIMARY,IDIndex,SubsetIndex SubsetIndex 767 const 522014 "Using where; Using temporary; Using filesort" 1 SIMPLE subsets eq_ref PRIMARY,IDIndex,SubsetIndex PRIMARY 771 sotero.subsets.Id,const 1 "Using where; Using index" 1 SIMPLE c ref IDIndex IDIndex 4 sotero.subsets.Id 12 "Using where" 1 SIMPLE c ref IDIndex IDIndex 4 sotero.subsets.Id 12 note the "using temporary; using filesort". When this query is run, I quickly run out of RAM (presumably b/c of the temp table), and then the HDD kicks in, and the query slows to a halt. I thought it might be an index issue, so I started adding a few that sort of made sense: Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment Index_comment chunks 0 PRIMARY 1 ChunkId A 17796190 NULL NULL BTREE chunks 1 ChunkHashIndex 1 ChunkHash A 243783 NULL NULL BTREE chunks 1 IDIndex 1 Id A 1483015 NULL NULL BTREE chunks 1 ChunkIndex 1 Chunk A 243783 NULL NULL BTREE chunks 1 ChunkTypeIndex 1 ChunkType A 2 NULL NULL BTREE chunks 1 chunkHashByChunkIDIndex 1 ChunkHash A 243783 NULL NULL BTREE chunks 1 chunkHashByChunkIDIndex 2 ChunkId A 17796190 NULL NULL BTREE chunks 1 chunkHashByChunkTypeIndex 1 ChunkHash A 243783 NULL NULL BTREE chunks 1 chunkHashByChunkTypeIndex 2 ChunkType A 261708 NULL NULL BTREE chunks 1 chunkHashByIDIndex 1 ChunkHash A 243783 NULL NULL BTREE chunks 1 chunkHashByIDIndex 2 Id A 17796190 NULL NULL BTREE But still using the temporary table. The db engine is MyISAM. How can I get rid of the using temporary; using filesort in this query? Just changing to InnoDB w/o explaining the underlying cause is not a particularly satisfying answer. Besides, if the solution is to just add the proper index, then that's much easier than migrating to another db engine.

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  • How do I select differing rows in two MySQL tables with the same structure?

    - by chiborg
    I have two tables, A and B, that have the same structure (about 30+ fields). Is there a short, elegant way to join these tables and only select rows where one or more columns differ? I could certainly write some script that creates the query with all the column names but maybe there is an SQL-only solution. To put it another way: Is there a short substitute to this: SELECT * FROM table_a a JOIN table_b b ON a.pkey=b.pkey WHERE a.col1 != b.col2 OR a.col2 != b.col2 OR a.col3 != b.col3 # .. repeat for 30 columns

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  • rookie MySql question about paging; Is one query enough?

    - by Camran
    I have managed to get paging to work, almost. I want to display to the user, total nr of records found, and the currently displayed records. Ex: 4000 found, displaying 0-100. I am testing this with the nr 2 (because I don't have that many records, have like 20). So I am using LIMIT $start, $nr_results; Do I have to make two queries in order to display the results the way I want, one query fetching all records and then make a mysql_num_rows to get all records, then the one with the LIMIT ? I have this: mysql_num_rows($qry_result); $total_pages = ceil($num_total / $res_per_page); //$res_per_page==2 and $num_total = 2 if ($p - 10 < 1) { $pagemin=1; } else { $pagemin = $p - 10; } if ($p + 10 $total_pages) { $pagemax = $total_pages; } else { $pagemax = $p + 10; } Here is the query: SELECT mt.*, fordon.*, boende.*, elektronik.*, business.*, hem_inredning.*, hobby.* FROM classified mt LEFT JOIN fordon ON fordon.classified_id = mt.classified_id LEFT JOIN boende ON boende.classified_id = mt.classified_id LEFT JOIN elektronik ON elektronik.classified_id = mt.classified_id LEFT JOIN business ON business.classified_id = mt.classified_id LEFT JOIN hem_inredning ON hem_inredning.classified_id = mt.classified_id LEFT JOIN hobby ON hobby.classified_id = mt.classified_id ORDER BY modify_date DESC LIMIT 0, 2 Thanks, if you need more input let me know. Basically Q is, do I have to make two queries?

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