select * from emp where salary > (select salary from emp where name='猪八戒');
1. select * from emp where dep_id in (select did from dept where dname in ('财务部','市场部'));
2. select * from emp where dep_id=(select did from dept where dname='财务部');
3. select * from (select * from emp where join_date > '2011-11-11') t1 left join dept on t1.dep_id=dept.did;