A script to change all tables and fields to the utf-8-bin collation in MYSQL

Can be done in a single command (rather than 148 of PHP):

mysql --database=dbname -B -N -e "SHOW TABLES" \
| awk '{print "SET foreign_key_checks = 0; ALTER TABLE", $1, "CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci; SET foreign_key_checks = 1; "}' \
| mysql --database=dbname &

You've got to love the commandline... (You might need to employ the --user and --password options for mysql).

EDIT: to avoid foreign key problems, added SET foreign_key_checks = 0; and SET foreign_key_checks = 1;

I think it's easy to do this in two steps runin PhpMyAdmin.
Step 1:

SELECT CONCAT('ALTER TABLE `', t.`TABLE_SCHEMA`, '`.`', t.`TABLE_NAME`,
 '` CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci;') as stmt 
FROM `information_schema`.`TABLES` t
WHERE 1
AND t.`TABLE_SCHEMA` = 'database_name'
ORDER BY 1

Step 2:
This query will output a list of queries, one for each table. You have to copy the list of queries, and paste them to the command line or to PhpMyAdmin's SQL tab for the changes to be made.

OK, I wrote this up taking into account what was said in this thread. Thanks for the help, and I hope this script will help out others. I don't have any warranty for its use, so PLEASE BACKUP before running it. It should work with all databases; and it worked great on my own.

EDIT: Added vars at the top for which charset/collate to convert to. EDIT2: Changes the database's and tables' default charset/collate

<?php

function MysqlError()
{
    if (mysql_errno())
    {
        echo "<b>Mysql Error: " . mysql_error() . "</b>\n";
    }
}

$username = "root";
$password = "";
$db = "database";
$host = "localhost";

$target_charset = "utf8";
$target_collate = "utf8_general_ci";

echo "<pre>";

$conn = mysql_connect($host, $username, $password);
mysql_select_db($db, $conn);

$tabs = array();
$res = mysql_query("SHOW TABLES");
MysqlError();
while (($row = mysql_fetch_row($res)) != null)
{
    $tabs[] = $row[0];
}

// now, fix tables
foreach ($tabs as $tab)
{
    $res = mysql_query("show index from {$tab}");
    MysqlError();
    $indicies = array();

    while (($row = mysql_fetch_array($res)) != null)
    {
        if ($row[2] != "PRIMARY")
        {
            $indicies[] = array("name" => $row[2], "unique" => !($row[1] == "1"), "col" => $row[4]);
            mysql_query("ALTER TABLE {$tab} DROP INDEX {$row[2]}");
            MysqlError();
            echo "Dropped index {$row[2]}. Unique: {$row[1]}\n";
        }
    }

    $res = mysql_query("DESCRIBE {$tab}");
    MysqlError();
    while (($row = mysql_fetch_array($res)) != null)
    {
        $name = $row[0];
        $type = $row[1];
        $set = false;
        if (preg_match("/^varchar\((\d+)\)$/i", $type, $mat))
        {
            $size = $mat[1];
            mysql_query("ALTER TABLE {$tab} MODIFY {$name} VARBINARY({$size})");
            MysqlError();
            mysql_query("ALTER TABLE {$tab} MODIFY {$name} VARCHAR({$size}) CHARACTER SET {$target_charset}");
            MysqlError();
            $set = true;

            echo "Altered field {$name} on {$tab} from type {$type}\n";
        }
        else if (!strcasecmp($type, "CHAR"))
        {
            mysql_query("ALTER TABLE {$tab} MODIFY {$name} BINARY(1)");
            MysqlError();
            mysql_query("ALTER TABLE {$tab} MODIFY {$name} VARCHAR(1) CHARACTER SET {$target_charset}");
            MysqlError();
            $set = true;

            echo "Altered field {$name} on {$tab} from type {$type}\n";
        }
        else if (!strcasecmp($type, "TINYTEXT"))
        {
            mysql_query("ALTER TABLE {$tab} MODIFY {$name} TINYBLOB");
            MysqlError();
            mysql_query("ALTER TABLE {$tab} MODIFY {$name} TINYTEXT CHARACTER SET {$target_charset}");
            MysqlError();
            $set = true;

            echo "Altered field {$name} on {$tab} from type {$type}\n";
        }
        else if (!strcasecmp($type, "MEDIUMTEXT"))
        {
            mysql_query("ALTER TABLE {$tab} MODIFY {$name} MEDIUMBLOB");
            MysqlError();
            mysql_query("ALTER TABLE {$tab} MODIFY {$name} MEDIUMTEXT CHARACTER SET {$target_charset}");
            MysqlError();
            $set = true;

            echo "Altered field {$name} on {$tab} from type {$type}\n";
        }
        else if (!strcasecmp($type, "LONGTEXT"))
        {
            mysql_query("ALTER TABLE {$tab} MODIFY {$name} LONGBLOB");
            MysqlError();
            mysql_query("ALTER TABLE {$tab} MODIFY {$name} LONGTEXT CHARACTER SET {$target_charset}");
            MysqlError();
            $set = true;

            echo "Altered field {$name} on {$tab} from type {$type}\n";
        }
        else if (!strcasecmp($type, "TEXT"))
        {
            mysql_query("ALTER TABLE {$tab} MODIFY {$name} BLOB");
            MysqlError();
            mysql_query("ALTER TABLE {$tab} MODIFY {$name} TEXT CHARACTER SET {$target_charset}");
            MysqlError();
            $set = true;

            echo "Altered field {$name} on {$tab} from type {$type}\n";
        }

        if ($set)
            mysql_query("ALTER TABLE {$tab} MODIFY {$name} COLLATE {$target_collate}");
    }

    // re-build indicies..
    foreach ($indicies as $index)
    {
        if ($index["unique"])
        {
            mysql_query("CREATE UNIQUE INDEX {$index["name"]} ON {$tab} ({$index["col"]})");
            MysqlError();
        }
        else
        {
            mysql_query("CREATE INDEX {$index["name"]} ON {$tab} ({$index["col"]})");
            MysqlError();
        }

        echo "Created index {$index["name"]} on {$tab}. Unique: {$index["unique"]}\n";
    }

    // set default collate
    mysql_query("ALTER TABLE {$tab}  DEFAULT CHARACTER SET {$target_charset} COLLATE {$target_collate}");
}

// set database charset
mysql_query("ALTER DATABASE {$db} DEFAULT CHARACTER SET {$target_charset} COLLATE {$target_collate}");

mysql_close($conn);
echo "</pre>";

?>