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

Question

Is there a SQL or PHP script that I can run that will change the default collation in all tables and fields in a database?

I can write one

Answer 1

Thanks @nlaq for the code, that got me started on the below solution.

I released a WordPress plugin without realising that WordPress doesn't set the collate automatically. So a lot of people using the plugin ended up with latin1_swedish_ci when it should have been utf8_general_ci.

Here's the code I added to the plugin to detect the latin1_swedish_ci collate and change it to utf8_general_ci.

Test this code before using it in your own plugin!

// list the names of your wordpress plugin database tables (without db prefix)
$tables_to_check = array(
    'social_message',
    'social_facebook',
    'social_facebook_message',
    'social_facebook_page',
    'social_google',
    'social_google_mesage',
    'social_twitter',
    'social_twitter_message',
);
// choose the collate to search for and replace:
$convert_fields_collate_from = 'latin1_swedish_ci';
$convert_fields_collate_to = 'utf8_general_ci';
$convert_tables_character_set_to = 'utf8';
$show_debug_messages = false;
global $wpdb;
$wpdb->show_errors();
foreach($tables_to_check as $table) {
    $table = $wpdb->prefix . $table;
    $indicies = $wpdb->get_results(  "SHOW INDEX FROM `$table`", ARRAY_A );
    $results = $wpdb->get_results( "SHOW FULL COLUMNS FROM `$table`" , ARRAY_A );
    foreach($results as $result){
        if($show_debug_messages)echo "Checking field ".$result['Field'] ." with collat: ".$result['Collation']."\n";
        if(isset($result['Field']) && $result['Field'] && isset($result['Collation']) && $result['Collation'] == $convert_fields_collate_from){
            if($show_debug_messages)echo "Table: $table - Converting field " .$result['Field'] ." - " .$result['Type']." - from $convert_fields_collate_from to $convert_fields_collate_to \n";
            // found a field to convert. check if there's an index on this field.
            // we have to remove index before converting field to binary.
            $is_there_an_index = false;
            foreach($indicies as $index){
                if ( isset($index['Column_name']) && $index['Column_name'] == $result['Field']){
                    // there's an index on this column! store it for adding later on.
                    $is_there_an_index = $index;
                    $wpdb->query( $wpdb->prepare( "ALTER TABLE `%s` DROP INDEX %s", $table, $index['Key_name']) );
                    if($show_debug_messages)echo "Dropped index ".$index['Key_name']." before converting field.. \n";
                    break;
                }
            }
            $set = false;

            if ( preg_match( "/^varchar\((\d+)\)$/i", $result['Type'], $mat ) ) {
                $wpdb->query( "ALTER TABLE `{$table}` MODIFY `{$result['Field']}` VARBINARY({$mat[1]})" );
                $wpdb->query( "ALTER TABLE `{$table}` MODIFY `{$result['Field']}` VARCHAR({$mat[1]}) CHARACTER SET {$convert_tables_character_set_to} COLLATE {$convert_fields_collate_to}" );
                $set = true;
            } else if ( !strcasecmp( $result['Type'], "CHAR" ) ) {
                $wpdb->query( "ALTER TABLE `{$table}` MODIFY `{$result['Field']}` BINARY(1)" );
                $wpdb->query( "ALTER TABLE `{$table}` MODIFY `{$result['Field']}` VARCHAR(1) CHARACTER SET {$convert_tables_character_set_to} COLLATE {$convert_fields_collate_to}" );
                $set = true;
            } else if ( !strcasecmp( $result['Type'], "TINYTEXT" ) ) {
                $wpdb->query( "ALTER TABLE `{$table}` MODIFY `{$result['Field']}` TINYBLOB" );
                $wpdb->query( "ALTER TABLE `{$table}` MODIFY `{$result['Field']}` TINYTEXT CHARACTER SET {$convert_tables_character_set_to} COLLATE {$convert_fields_collate_to}" );
                $set = true;
            } else if ( !strcasecmp( $result['Type'], "MEDIUMTEXT" ) ) {
                $wpdb->query( "ALTER TABLE `{$table}` MODIFY `{$result['Field']}` MEDIUMBLOB" );
                $wpdb->query( "ALTER TABLE `{$table}` MODIFY `{$result['Field']}` MEDIUMTEXT CHARACTER SET {$convert_tables_character_set_to} COLLATE {$convert_fields_collate_to}" );
                $set = true;
            } else if ( !strcasecmp( $result['Type'], "LONGTEXT" ) ) {
                $wpdb->query( "ALTER TABLE `{$table}` MODIFY `{$result['Field']}` LONGBLOB" );
                $wpdb->query( "ALTER TABLE `{$table}` MODIFY `{$result['Field']}` LONGTEXT CHARACTER SET {$convert_tables_character_set_to} COLLATE {$convert_fields_collate_to}" );
                $set = true;
            } else if ( !strcasecmp( $result['Type'], "TEXT" ) ) {
                $wpdb->query( "ALTER TABLE `{$table}` MODIFY `{$result['Field']}` BLOB" );
                $wpdb->query( "ALTER TABLE `{$table}` MODIFY `{$result['Field']}` TEXT CHARACTER SET {$convert_tables_character_set_to} COLLATE {$convert_fields_collate_to}" );
                $set = true;
            }else{
                if($show_debug_messages)echo "Failed to change field - unsupported type: ".$result['Type']."\n";
            }
            if($set){
                if($show_debug_messages)echo "Altered field success! \n";
                $wpdb->query( "ALTER TABLE `$table` MODIFY {$result['Field']} COLLATE $convert_fields_collate_to" );
            }
            if($is_there_an_index !== false){
                // add the index back.
                if ( !$is_there_an_index["Non_unique"] ) {
                    $wpdb->query( "CREATE UNIQUE INDEX `{$is_there_an_index['Key_name']}` ON `{$table}` ({$is_there_an_index['Column_name']})", $is_there_an_index['Key_name'], $table, $is_there_an_index['Column_name'] );
                } else {
                    $wpdb->query( "CREATE UNIQUE INDEX `{$is_there_an_index['Key_name']}` ON `{$table}` ({$is_there_an_index['Column_name']})", $is_there_an_index['Key_name'], $table, $is_there_an_index['Column_name'] );
                }
            }
        }
    }
    // set default collate
    $wpdb->query( "ALTER TABLE `{$table}` DEFAULT CHARACTER SET {$convert_tables_character_set_to} COLLATE {$convert_fields_collate_to}" );
    if($show_debug_messages)echo "Finished with table $table \n";
}
$wpdb->hide_errors();