mysql更新数据，条件为实时查询出来的数据

--将更新条件保存到临时表里
CREATE TABLE tmp3 AS (SELECT  username FROM oa_user  WHERE username NOT IN (SELECT  username FROM nst_t_account));
--更新表数据，条件从临时表里取
UPDATE oa_user SET usr_update=NOW() WHERE username IN (SELECT username FROM tmp3);
--删除临时表
DROP TABLE tmp3;