ALTER TABLE erp_diff_order ADD COLUMN created_date_tmp int(11) default 0; UPDATE erp_diff_order SET created_date_tmp=UNIX_TIMESTAMP(created_date); ALTER TABLE erp_diff_order DROP COLUMN created_date; ALTER TABLE erp_diff_order ADD COLUMN created_date int(11) default 0; UPDATE erp_diff_order SET created_date=created_date_tmp; ALTER TABLE erp_diff_order DROP COLUMN created_date_tmp;