按理说，应该从 下面的两个select SQL中取一个得到idx，然后再执行
delete from user where idx in (xxx,xxx);即可

但是，我想一次性删除，即不再另外运行一条 delete from语句

get的两条语句均可以。但是将里面的
select * from
改为 delete from 就不成功了，

delete from user b join (select * from user a where idx in (29,35)) c on (b.source_user = c.source_user and b.target_user = c.target_user) or (b.source_user = c.target_user and b.target_user = c.source_user);

select a.*  from user a join user b  on  ((b.source_user = a.source_user and b.target_user = a.target_user) or (b.source_user = a.target_user and b.target_user = a.source_user))  where b.idx in (29,35); 

select b.*  from user b  join (select * from user a where idx in (29)) c  on (b.source_user = c.source_user and b.target_user = c.target_user) or (b.source_user = c.target_user and b.target_user = c.source_user)