3.SQL学习之多表查询⼗个练习题准备数据
CREATE DATABASE db2;
-- 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)-- 部门位置
);
-- 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
-- ⼯资等级表
CREATE TABLE salarygrade (
grade INT PRIMARY KEY,
losalary INT,
hisalary INT
);
-- 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);
表中数据查询
SELECT*FROM dept;-- 部门表
SELECT*FROM emp;-- 员⼯表
SELECT*FROM job;-- 职务表
SELECT*FROM salarygrade;-- ⼯资等级表
1.查询所有员⼯信息。显⽰员⼯编号，员⼯姓名，⼯资，职务名称，职务描述
SELECT e.`id`,e.`ename`,e.`salary`,j.`jname`,j.`description`
FROM emp e
INNER JOIN job j
ON e.`job_id`=j.`id`;
2.查询所有员⼯信息。显⽰员⼯编号，员⼯姓名，⼯资，职务名称，职务描述，部门名称，部门位置
SELECT e.`id`,e.`ename`,e.`salary`,j.`jname`,j.`description`,d.`dname`,d.`loc`
FROM emp e
INNER JOIN dept d
ON e.`dept_id`=d.`id`
INNER JOIN job j
ON e.`job_id`=j.`id`
3.查询所有员⼯信息。显⽰员⼯姓名，⼯资，职务名称，职务描述，部门名称，部门位置，⼯资等级
SELECT e.`ename`,e.`salary`,j.`jname`,j.`description`,d.`dname`,d.`loc`,s.grade
FROM emp e
INNER JOIN dept d
ON e.`dept_id`=d.`id`
INNER JOIN job j
多表left joinON e.`job_id`=j.`id`
INNER JOIN salarygrade s
ON e.`salary`BETWEEN s.losalary AND s.hisalary;
4.查询经理的信息。显⽰员⼯姓名，⼯资，职务名称，职务描述，部门名称，部门位置，⼯资等级
SELECT e.`ename`,e.`salary`,j.`jname`,j.`description`,d.`dname`,d.`loc`,s.`grade`
FROM emp e
INNER JOIN dept d
ON e.`dept_id`=d.`id`
INNER JOIN job j
ON e.`job_id`=j.`id`
INNER JOIN salarygrade s
ON e.`salary`BETWEEN s.`losalary`AND s.`hisalary`
WHERE j.`jname`='经理';
5.查询出部门编号、部门名称、部门位置、部门⼈数
SELECT d.*,COUNT(*)部门⼈数
FROM emp e
INNER JOIN dept d
ON e.`dept_id`=d.`id`
GROUP BY e.`dept_id`
6.查询所有员⼯信息。显⽰员⼯信息和部门名称，没有员⼯的部门也要显⽰
SELECT e.*,d.`dname`
FROM emp e
RIGHT JOIN dept d
ON e.`dept_id`=d.`id`;
7.查询所有员⼯信息。显⽰员⼯姓名，员⼯⼯资，职务名称，⼯资等级，并按⼯资升序排序
SELECT e.`ename`,e.`salary`,j.`jname`,s.`grade`
FROM emp e
INNER JOIN job j
ON e.`job_id`=j.`id`
INNER JOIN salarygrade s
ON e.`salary`BETWEEN s.`losalary`AND s.`hisalary`
ORDER BY e.salary ASC;
8.列出所有员⼯的姓名及其直接上级的姓名，没有领导的员⼯也需要显⽰
ame,e2.`ename`
FROM emp e
LEFT JOIN emp e2
ON e.`mgr`=e2.`id`;
9.查询⼊职期早于直接上级的所有员⼯编号、姓名、部门名称
SELECT e.`id`,e.`ename`,d.`dname`
FROM emp e
INNER JOIN emp e2
ON e.`mgr`=e2.`id`
INNER JOIN dept d
ON e.`dept_id`=d.`id`
WHERE e2.`joindate`>e.`joindate`;
10.查询⼯资⾼于公司平均⼯资的所有员⼯信息。显⽰员⼯信息，部门名称，上级领导，⼯资等级
SELECT e.*,d.`dname`,e2.`ename`,s.`grade`
FROM emp e
INNER JOIN emp e2
ON e.`mgr`=e2.`id`
INNER JOIN dept d
ON e.`dept_id`=d.`id`
INNER JOIN salarygrade s
ON e.`salary`BETWEEN s.`losalary`AND s.`hisalary` WHERE e.`salary`>(SELECT AVG(salary)FROM emp);

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