第一步:查询每个雇员的编号、姓名、职位、雇佣日期、工资
SELECT e.empno,e.ename,e.job,e.sal,e.hiredate FROM emp e ;
第二步:增加工资等级的判断
SELECT e.empno,e.ename,e.job,e.sal,e.hiredate,s.grade FROM emp e ,salgrade s WHERE e.sal BETWEEN s.losal AND s.hisal ;
第三步:增加部门表信息
SELECT e.empno,e.ename,e.job,e.sal,e.hiredate,s.grade,d.dname,d.loc FROM emp e ,salgrade s,dept d WHERE e.sal BETWEEN s.losal AND s.hisal AND e.deptno=d.deptno ;