16子嵌套

1. 查询工资高于1号部门平均工资的员工信息

select avg(sal) from emp where deptno=1;

select * from emp where sal>2330;

合并上面两条SQL select * from emp where sal>(select avg(sal) from emp where deptno=1);

2. 查询工资最高的员工信息

select max(sal) from emp;

select * from emp where sal=(select max(sal) from emp);

3. 查询工资高于2号部门最低工资的员工信息

select * from emp where sal>(select min(sal) from emp where deptno=2);

4. 查询和孙悟空相同工作的其它员工信息

select job from emp where ename="XXX";

select * from emp where job=(select job from emp where ename="孙悟空") and ename!="XXX";

5. 查询拿最低工资员工的同事们的信息(同事指相同部门)

得到最低工资

select min(sal) from emp;

得到最低工资的员工的部门编号

select deptno from emp where sal=(select min(sal) from emp);

得到上面部门编号的员工 并且排除掉最低工资的员工

select * from emp where deptno=(select deptno from emp where sal=(select min(sal) from emp)) and sal!=(select min(sal) from emp);

6. 查询白骨精的部门信息(需要用到部门表dept)

select deptno from emp where ename="白骨精";

select * from dept where deptno=(select deptno from emp where ename="白骨精");