mysql多表练习2

数据表有下面几个

emp表

dept表

salgrade表

查询练习1

要求查询研发部的所有员工及平均工资

SELECT
  e.*,
  s.grade
FROM
  emp AS e,
  salgrade AS s,
  dept AS d
WHERE
  e.deptid = d.id
  AND (e.salary BETWEEN s.losal AND s.hisal)
  AND d.NAME = '研发部';

查询结果

练习2

查询研发部平均工资

select avg(e.salary) as '平均工资' from emp as e,dept as d where e.deptid=d.id and d.name = '研发部';

查询结果

练习3

查询工资比灭绝高的员工信息

-- 先查询灭绝的工资
select salary from emp where name='灭绝';
-- 查询工资比灭绝高的员工
select * from emp where salary>(select salary from emp where name='灭绝');

查询结果