select * from A where id in (select id from B)
等价于:
for select id from B
for select * from A where A.id = B.id

select * from A where exists (select 1 from B where B.id = A.id)
等价于
for select * from A
for select * from B where B.id = A.id

/** 执行时间：0.313s **/
SELECT SQL_NO_CACHE * FROM rocky_member m WHERE EXISTS (SELECT 1 FROM rocky_vip_appro a WHERE m.ID = a.user_id AND a.passed = 1);
/** 执行时间：0.160s **/
SELECT SQL_NO_CACHE * FROM rocky_member m WHERE m.ID in(SELECT ID FROM rocky_vip_appro WHERE passed = 1);