Autarchy of the Private Cave » latin1 https://bogdan.org.ua Tiny bits of bioinformatics, [web-]programming etc Wed, 28 Dec 2022 16:09:04 +0000 en-US hourly 1 https://wordpress.org/?v=3.8.27 Convert MySQL database from one encoding/collation into anotherhttps://bogdan.org.ua/2008/02/08/convert-mysql-database-from-one-encodingcollation-into-another.html https://bogdan.org.ua/2008/02/08/convert-mysql-database-from-one-encodingcollation-into-another.html#comments Fri, 08 Feb 2008 19:17:45 +0000 http://bogdan.org.ua/2008/02/08/convert-mysql-database-from-one-encodingcollation-into-another.html Most frequent use: convert database from latin1_swedish to utf8_general_ci.
Original script found at: MySQL and UTF-8.

Update: the original script had an error, it would generate queries likes this one (note the bold part):

ALTER TABLE `links` CHANGE `link_rel` `link_rel` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL DEFAULT NULL;

This is clearly wrong syntax (and logic). I fixed this by making comparison to NULL strict (with three equal signs instead of two):

// Does the field default to null, a string, or nothing?
if ($row['Default'] === NULL)

Update 2: based on comment by banesto, I modified the script; now it does not require specifying the from_collation, it’s sufficient to specify to_collation (which will be used for all the fields and tables). The modified code is:

if ($row['Collation'] == ” || $row['Collation'] == $convert_to)
continue;

Update 3: the long-lasting, re-appearing NOT NULL DEFAULT NULL problem is finally fixed.

Update 4: incorporated Russ’s fix to skip numeric fields (in order to leave autoincrement values intact).

Here’s the script itself: (to copy-paste: first click the “Plain text” header)

  1. <?php
  2. // Original script (v1.0) by/from: http://www.phpwact.org/php/i18n/utf-8/mysql
  3. // Improved/modified (v1.05) by Bogdan http://bogdan.org.ua/
  4. // Last updated: 2010-06-28
  5.  
  6. // this script will output all queries needed to change all fields/tables to a different collation
  7. // it is HIGHLY suggested you make a MySQL backup prior to running any of the generated queries
  8.  
  9. // this code is provided AS IS and without any warranty
  10.  
  11. // add text/plain header when used not as a CLI script; PHP CLI SAPI shouldn't output headers
  12. header("Content-Type: text/plain");
  13.  
  14. // precaution
  15. die("Make a backup of your MySQL database, then remove this line from the code!");
  16.  
  17. set_time_limit(0);
  18.  
  19. // collation you want to change to:
  20. $convert_to   = 'utf8_general_ci';
  21.  
  22. // character set of new collation:
  23. $character_set= 'utf8';
  24.  
  25. // DB login information - *modify before use*
  26. $username = 'user';
  27. $password = 'pass';
  28. $database = 'database_name';
  29. $host     = 'localhost';
  30.  
  31. //-- usually, there is nothing to modify below this line --//
  32.  
  33. // show TABLE alteration queries?
  34. $show_alter_table = true;
  35. // show FIELD alteration queries?
  36. $show_alter_field = true;
  37.  
  38. mysql_connect($host, $username, $password);
  39. mysql_select_db($database);
  40.  
  41. $rs_tables = mysql_query(" SHOW TABLES ") or die(mysql_error());
  42.  
  43. while ($row_tables = mysql_fetch_row($rs_tables)) {
  44.     $table = mysql_real_escape_string($row_tables&#91;0&#93;);
  45.    
  46.     // Alter table collation
  47.     // ALTER TABLE `account` DEFAULT CHARACTER SET utf8
  48.     if ($show_alter_table)
  49.         echo("ALTER TABLE `$table` DEFAULT CHARACTER SET $character_set;\n");
  50.  
  51.     $rs = mysql_query(" SHOW FULL FIELDS FROM `$table` ") or die(mysql_error());
  52.  
  53.     while ( $row = mysql_fetch_assoc($rs) ) {
  54.        
  55.         if ( $row&#91;'Collation'&#93; == '' || $row&#91;'Collation'&#93; == $convert_to )
  56.            continue;
  57.  
  58.         // Is the field allowed to be null?
  59.         if ( $row&#91;'Null'&#93; == 'YES' )
  60.            $nullable = ' NULL ';
  61.         else
  62.             $nullable = ' NOT NULL ';
  63.  
  64.         // Does the field default to null, a string, or nothing?
  65.         if ( $row&#91;'Default'&#93; === NULL && $row&#91;'Null'&#93; == 'YES' )
  66.            $default = " DEFAULT NULL ";
  67.         elseif ( $row&#91;'Default'&#93; != '' )
  68.            $default = " DEFAULT '".mysql_real_escape_string($row&#91;'Default'&#93;)."'";
  69.        else
  70.             $default = '';
  71.  
  72.         // sanity check and fix:
  73.         if ($nullable == ' NOT NULL ' && $default == ' DEFAULT NULL ') {
  74.             $default = '';
  75.             echo "/* Warning: wrong combination of 'default value' and 'NULL-flag' detected - and fixed! */\n";
  76.             echo "/* Diagnostics: row&#91;Null&#93; = '$row&#91;Null&#93;', row&#91;Default&#93; = " . mysql_real_escape_string($row&#91;'Default'&#93;) . ", MySQL version: " . mysql_get_server_info() . " */\n";
  77.        }
  78.  
  79.         // Don't alter INT columns: no collations, and altering them drops autoincrement values
  80.         if (strpos($row&#91;'Type'&#93;, 'int') !== false) {
  81.            $show_alter_field = False;
  82.         }
  83.         else {
  84.             $show_alter_field = True;
  85.         }
  86.  
  87.         // Alter field collation:
  88.         // ALTER TABLE `tab` CHANGE `field` `field` CHAR( 5 ) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL
  89.         if ($show_alter_field) {
  90.             $field = mysql_real_escape_string($row&#91;'Field'&#93;);
  91.            echo "ALTER TABLE `$table` CHANGE `$field` `$field` $row&#91;Type&#93; CHARACTER SET $character_set COLLATE $convert_to $nullable $default;\n";
  92.         }
  93.     }
  94. }
  95. ?>

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