oracle中关于emp表的一些问题，急求！ 书写以下SQL（要求一条SQL语句完成） 列出工资比

1. select * from emp where sal>(select max(sal)/2 from emp);

2. select b.dname from

   (select deptno,avg(sal) from emp group by deptno having avg(sal)>(select avg(sal) from emp)) a

   left join dept b on b.deptno=a.deptno

3. select a.* from 

   (select job,count(*) cnt from emp group by job order by cnt desc) a where rownum <3

4. select b.dname from 

   (select deptno,count(*) cnt from emp group by deptno order by cnt desc) a 

   left join dept b on a.deptno=b.deptno where rownum=1

5. select b.dname from 

   (select deptno, max(sal)-min(sal) saldec from emp group by deptno order by saldec desc) a

   left join dept b on a.deptno=b.deptno

   where rownum=1

结果都能查出来，至于效率是不是最高的，自己分析执行计划吧

不是吧！这么多？参数呢？