Mysql数据库多表查询自用综合练习总结

部门表

CREATE TABLE dept (
				  id INT PRIMARY KEY PRIMARY KEY, -- 部门id
				  dname VARCHAR(50), -- 部门名称
				  loc VARCHAR(50) -- 部门所在地
				);
				
				-- 添加4个部门
				INSERT INTO dept(id,dname,loc) VALUES 
				(10,'教研部','北京'),
				(20,'学工部','上海'),
				(30,'销售部','广州'),
				(40,'财务部','深圳');
				
				
				
				-- 职务表，职务名称，职务描述
				CREATE TABLE job (
				  id INT PRIMARY KEY,
				  jname VARCHAR(20),
				  description VARCHAR(50)
				);
				
				-- 添加4个职务
				INSERT INTO job (id, jname, description) VALUES
				(1, '董事长', '管理整个公司，接单'),
				(2, '经理', '管理部门员工'),
				(3, '销售员', '向客人推销产品'),
				(4, '文员', '使用办公软件');
				
				
				
				-- 员工表
				CREATE TABLE emp (
				  id INT PRIMARY KEY, -- 员工id
				  ename VARCHAR(50), -- 员工姓名
				  job_id INT, -- 职务id
				  mgr INT , -- 上级领导
				  joindate DATE, -- 入职日期
				  salary DECIMAL(7,2), -- 工资
				  bonus DECIMAL(7,2), -- 奖金
				  dept_id INT, -- 所在部门编号
				  CONSTRAINT emp_jobid_ref_job_id_fk FOREIGN KEY (job_id) REFERENCES job (id),
				  CONSTRAINT emp_deptid_ref_dept_id_fk FOREIGN KEY (dept_id) REFERENCES dept (id)
				);
				
				-- 添加员工
				INSERT INTO emp(id,ename,job_id,mgr,joindate,salary,bonus,dept_id) VALUES 
				(1001,'孙悟空',4,1004,'2000-12-17','8000.00',NULL,20),
				(1002,'卢俊义',3,1006,'2001-02-20','16000.00','3000.00',30),
				(1003,'林冲',3,1006,'2001-02-22','12500.00','5000.00',30),
				(1004,'唐僧',2,1009,'2001-04-02','29750.00',NULL,20),
				(1005,'李逵',4,1006,'2001-09-28','12500.00','14000.00',30),
				(1006,'宋江',2,1009,'2001-05-01','28500.00',NULL,30),
				(1007,'刘备',2,1009,'2001-09-01','24500.00',NULL,10),
				(1008,'猪八戒',4,1004,'2007-04-19','30000.00',NULL,20),
				(1009,'罗贯中',1,NULL,'2001-11-17','50000.00',NULL,10),
				(1010,'吴用',3,1006,'2001-09-08','15000.00','0.00',30),
				(1011,'沙僧',4,1004,'2007-05-23','11000.00',NULL,20),
				(1012,'李逵',4,1006,'2001-12-03','9500.00',NULL,30),
				(1013,'小白龙',4,1004,'2001-12-03','30000.00',NULL,20),
				(1014,'关羽',4,1007,'2002-01-23','13000.00',NULL,10);
				
				
				
				-- 工资等级表
				CREATE TABLE salarygrade (
				  grade INT PRIMARY KEY,   -- 级别
				  losalary INT,  -- 最低工资
				  hisalary INT -- 最高工资
				);
				
				-- 添加5个工资等级
				INSERT INTO salarygrade(grade,losalary,hisalary) VALUES 
				(1,7000,12000),
				(2,12010,14000),
				(3,14010,20000),
				(4,20010,30000),
				(5,30010,99990);
           

练习

1. 查询所有员工信息，员工编号，员工姓名，工资，职务名称，职务描述

   select * from emp e left join job j on e.job_id=j.id;

   

   2.查询员工编号，名字，工资，职务，职务描述，部门位置：

select e.id,ename,salary,jname, description,loc from( emp e left join dept d on e.dept_id=d.id ) left join job j on e.job_id=j.id;

           

1. 查询员工姓名，工资，工资等级

select ename, salary, grade from emp e ,salarygrade s where e.salary  between s.losalary and s.hisalary;
           

4. 查询员工姓名，工资，职务名称，和职务描述，部门位置，工资等级

select ename, salary, jname, description,loc ,grade   from ((emp e left join dept d on e.dept_id=d.id) left join job j on e.job_id=j.id)  ,salarygrade s where salary between s.losalary and s.hisalary;
           

5. 查询出部门编号，部门名称，部门位置，部门人数

select j.id ,jname,loc,count(jname) from( emp e left join job j on e.job_id=j.id ) left join dept d on e.dept_id=d.id group by e.job_id ;
           

6. 查询所有员工姓名，以及其上司，没有的上司的员工也需要查询

select e.ename,b.ename BOSS from emp e left join emp b on e.mgr=b.id;
```BOSS   是 b.ename的别名