Mysql – Table size reduce with help changing collation charset [MySQL]

Yes, you can set the default character set and collation on various levels.

First, in your question, on the database level:

CREATE DATABASE IF NOT EXISTS foo 
 DEFAULT CHARACTER SET = 'utf8' DEFAULT COLLATE 'utf8_general_ci'

or

ALTER DATABASE foo
 DEFAULT CHARACTER SET = 'utf8' DEFAULT COLLATE 'utf8_general_ci'

All new tables in that database should be created with the new character set and database if it's not specified in the table creation command (if it is specified in table command, the specification will override the database default).

You can set the default at a server level (so that all tables are created with the default for all databases unless explicitly stated otherwise) by providing the --character-set-server and --collation-server options in your my.cnf and restarting the server.

And finally, verify the client connection settings. This doc explains how the client connection can fine-tune (and override) the default settings.

I found an answer on this website: http://kb.siteground.com/article/How_to_change_the_collation_for_all_tables_in_db_to_UTF8.html

I cleaned up the code to print out better from a linux shell and added the $new_charset and $new_collation variables to the alter database statement.

vi change_collation_everything.php

<?php

// Configuration Section
$server = 'localhost'; //probably localhost but change if required
$username = 'root';
$password = 'password';
$database = 'database';
$new_charset = 'latin1'; 
$new_collation = 'latin1_general_cs';

// Connect to database
$db = mysql_connect($server, $username, $password); if(!$db) die("Cannot connect to database server -".mysql_error());
$select_db = mysql_select_db($database); if (!$select_db) die("could not select $database: ".mysql_error());

// change database collation
mysql_query("ALTER DATABASE $database DEFAULT CHARACTER SET $new_charset COLLATE $new_collation");

// Loop through all tables changing collation
$result=mysql_query('show tables');
while($tables = mysql_fetch_array($result)) {
    $table = $tables[0];
    mysql_query("ALTER TABLE $table DEFAULT CHARACTER SET $new_charset COLLATE $new_collation");

    // loop through each column changing collation
    $columns = mysql_query("SHOW FULL COLUMNS FROM $table where collation is not null");
    while($cols = mysql_fetch_array($columns)) {
        $column = $cols[0];
        $type = $cols[1];
        mysql_query("ALTER TABLE $table MODIFY $column $type CHARACTER SET $new_charset COLLATE $new_collation");
        print "changed $table collation of $column to $new_collation\n";
    }

    print "changed collation of $table to $new_collation\n";
}
print 'The collation of your database has been successfully changed!\n';
?>

I tested the answer on my own database changing from charset latin7 to latin1 and latin7_general_cs to latin1_general_cs for the collation.

I chose _cs instead of _ci for the collation because if you choose _ci which is the default collation for charset latin_1, the collation no longer shows up in the show create table tablename column output.

Try it out

$> php change_collation_everything.php

You can see all of the available charsets and their corresponding collations with the show collation sql query