MySQL基础之多表查询案例分享

create table salgrade(
grade int,
losal int,
hisal int
) comment '薪资等级表';
insert into salgrade values (1,0,3000);
insert into salgrade values (2,3001,5000);
insert into salgrade values (3,5001,8000);
insert into salgrade values (4,8001,10000);
insert into salgrade values (5,10001,15000);
insert into salgrade values (6,15001,20000);
insert into salgrade values (7,20001,25000);
insert into salgrade values (8,25001,30000);

select e.name , e.age , e.job , d.name from emp e , dept d where e.dept_id = d.id;

select e.name , e.age , e.job , d.name from emp e inner join dept d on e.dept_id =d.id where e.age < 30;

select distinct d.id , d.name from emp e , dept d where e.dept_id = d.id;

select e.*, d.name from emp e left join dept d on e.dept_id = d.id where e.age >40 ;

-- 方式一
select e.* , s.grade , s.losal, s.hisal from emp e , salgrade s where e.salary >=
s.losal and e.salary <= s.hisal;
-- 方式二
select e.* , s.grade , s.losal, s.hisal from emp e , salgrade s where e.salary
between s.losal and s.hisal;