Mysql資料庫多表查詢自用綜合練習總結

部門表

CREATE TABLE dept (
				  id INT PRIMARY KEY PRIMARY KEY, -- 部門id
				  dname VARCHAR(50), -- 部門名稱
				  loc VARCHAR(50) -- 部門所在地
				);
				
				-- 添加4個部門
				INSERT INTO dept(id,dname,loc) VALUES 
				(10,'教研部','北京'),
				(20,'學工部','上海'),
				(30,'銷售部','廣州'),
				(40,'财務部','深圳');
				
				
				
				-- 職務表，職務名稱，職務描述
				CREATE TABLE job (
				  id INT PRIMARY KEY,
				  jname VARCHAR(20),
				  description VARCHAR(50)
				);
				
				-- 添加4個職務
				INSERT INTO job (id, jname, description) VALUES
				(1, '董事長', '管理整個公司，接單'),
				(2, '經理', '管理部門員工'),
				(3, '銷售員', '向客人推銷産品'),
				(4, '文員', '使用辦公軟體');
				
				
				
				-- 員工表
				CREATE TABLE emp (
				  id INT PRIMARY KEY, -- 員工id
				  ename VARCHAR(50), -- 員工姓名
				  job_id INT, -- 職務id
				  mgr INT , -- 上級上司
				  joindate DATE, -- 入職日期
				  salary DECIMAL(7,2), -- 工資
				  bonus DECIMAL(7,2), -- 獎金
				  dept_id INT, -- 所在部門編号
				  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)
				);
				
				-- 添加員工
				INSERT INTO emp(id,ename,job_id,mgr,joindate,salary,bonus,dept_id) VALUES 
				(1001,'孫悟空',4,1004,'2000-12-17','8000.00',NULL,20),
				(1002,'盧俊義',3,1006,'2001-02-20','16000.00','3000.00',30),
				(1003,'林沖',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,'劉備',2,1009,'2001-09-01','24500.00',NULL,10),
				(1008,'豬八戒',4,1004,'2007-04-19','30000.00',NULL,20),
				(1009,'羅貫中',1,NULL,'2001-11-17','50000.00',NULL,10),
				(1010,'吳用',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,'小白龍',4,1004,'2001-12-03','30000.00',NULL,20),
				(1014,'關羽',4,1007,'2002-01-23','13000.00',NULL,10);
				
				
				
				-- 工資等級表
				CREATE TABLE salarygrade (
				  grade INT PRIMARY KEY,   -- 級别
				  losalary INT,  -- 最低工資
				  hisalary INT -- 最高工資
				);
				
				-- 添加5個工資等級
				INSERT INTO salarygrade(grade,losalary,hisalary) VALUES 
				(1,7000,12000),
				(2,12010,14000),
				(3,14010,20000),
				(4,20010,30000),
				(5,30010,99990);
           

練習

1. 查詢所有員工資訊，員工編号，員工姓名，工資，職務名稱，職務描述

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

   

   2.查詢員工編号，名字，工資，職務，職務描述，部門位置：

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. 查詢員工姓名，工資，工資等級

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

4. 查詢員工姓名，工資，職務名稱，和職務描述，部門位置，工資等級

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. 查詢出部門編号，部門名稱，部門位置，部門人數

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. 查詢所有員工姓名，以及其上司，沒有的上司的員工也需要查詢

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