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);
在这个案例中，我们主要运用上面所讲解的多表查询的语法，完成以下的12个需求即可，而这里主要涉及到的表就三张：emp员工表、dept部门表、salgrade薪资等级表 。
表: emp , dept
连接条件: emp.dept_id = dept.id
select e.name , e.age , e.job , d.name from emp e , dept d where e.dept_id = d.id;
表: emp , dept
连接条件: emp.dept_id = dept.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;
表: emp , dept
连接条件: emp.dept_id = dept.id
select distinct d.id , d.name from emp e , dept d where e.dept_id = d.id;
表: emp , dept
连接条件: emp.dept_id = dept.id
select e.*, d.name from emp e left join dept d on e.dept_id = d.id where e.age >40 ;
表: emp , salgrade
连接条件 : emp.salary >= salgrade.losal and emp.salary <= salgrade.hisal
-- 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;
