-- Drop `tid` from thread (if it exists) SET @s = (SELECT IF( (SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS WHERE table_name = '%TABLE_PREFIX%thread' AND table_schema = DATABASE() AND column_name = 'tid' ) > 0, "ALTER TABLE `%TABLE_PREFIX%thread` DROP COLUMN `tid`", "SELECT 1" )); PREPARE stmt FROM @s; EXECUTE stmt; DROP TABLE `%TABLE_PREFIX%ticket_attachment`; OPTIMIZE TABLE `%TABLE_PREFIX%ticket`; OPTIMIZE TABLE `%TABLE_PREFIX%thread`;