mysql - 需要在两个表上写查询

Question

我有两张桌子

Member (member_id,...)
friend-requests(member_id, friend_id)

我需要从 member_id 为 19 且不在列friend_id 中的成员表中获取所有记录

Answer 1

select * from member join friend-requests
on member.member_id=friend_requests.member_id
where
member.member_id=19
and
not exists (select f.member_id from friend-requests f where f.mmeber_id = member.member_id)

Answer 2

Select m.* from Member as m 
where member_id=19 and 
member_id not in (select friend_id from friend_requests where member_id=19)