select * from emp where sal<(select avg(sal) from emp);

select * from emp where hiredate= (select MIN（hiredate） from emp);

 select* from emp

 where (job,sal) =( select job,sal

 from emp

 where ename ='scott') and ename <>'scott';

  select * from emp where sal in (select sal from emp where job = 'manager');

select* from emp where sal not in(select sal from emp where job='manager');

 select* from emp where sal = any(select sal from emp where job='manager');

select* from emp where sal > any(select sal from emp where job='manager');

 select* from emp where sal < any(select sal from emp where job='manager');

 select job,count(empno),avg(sal) from emp group by job 
 having avg(sal)>(select avg(sal) from emp);

 select e.empno,e.ename,e.job,

 (select d.dname from dept d whered.deptno=e.deptno)from emp e;

 select d.dname,d.loc,count(e.empno)

 from emp e,dept d

 where e.deptno(+)=d.deptno

 group by d.dname,d.loc;

  分步1： select d.deptno,d.dname,d.locfrom dept d;

  分步2：select deptno,count(empno)from emp group by deptno;



 正确的查询：

 select d.deptno,d.dname,d.loc，temp.count 
 from dept d,(select deptno,count(empno) count from emp
 group by deptno) temp 
 where d.deptno=temp.deptno(+);