IF (SELECT count(user_id) FROM user_group where group_id != 1 and user_id=505) = 0 INSERT INTO user_group (user_id,group_id) VALUES ('505','1766' ); else update user_group SET user_id='505',group_i...
user表: user_right表: user_right 添加了一个联合索引 (userid,chusheng) SELECT * FROM user AS a LEFT JOIN user_right AS b ON a.id = b.userid WHERE b.chusheng = 1 我想使用user_right 表的这个索引 结...