MySQL~有关员工部门表的练习题
-- 部门表
CREATE TABLE dept (
id INT 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');SELECT * FROM dept;-- 职务表
CREATE TABLE job (
id INT PRIMARY KEY,
jname VARCHAR(20), -- 职务名称
description VARCHAR(50) –- 职务描述
);-- 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);SELECT * FROM dept;-- 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);-- 需求：
-- 1.查询所有员工信息。
查询员工编、员工姓名、工资、职务名称、职务描述
-- 隐式查询 --
SELECT
emp.id,
emp.ename,
emp.salary,
job.jname,
job.description
FROM emp,job
WHERE emp.job_id=job.id;-- 显式查询 --
SELECT
emp.id,
emp.ename,
emp.salary,
job.jname,
job.description
FROM emp INNER JOIN job ON emp.job_id=job.id;
-- 2.查询员工编号、员工姓名、工资、职务名称、职务描述、部门名称、部门位置
-- 隐式查询 --
SELECT
emp.id,
emp.ename,
emp.salary,
job.jname,
job.description,
dept.dname,
dept.loc
FROM emp,job,dept
WHERE emp.job_id=job.id AND emp.dept_id=dept.id;-- 显式查询 --
SELECT
emp.id,
emp.ename,
emp.salary,
job.jname,
job.description,
dept.dname,
dept.loc
FROM emp
INNER JOIN job ON emp.job_id=job.id
INNER JOIN dept ON emp.dept_id=dept.id;
-- 3.查询员工姓名、工资、工资等级
-- 简化查询 --
SELECT
emp.ename,
emp.salary,
t1.*
FROM emp,
salarygrade t1
WHERE emp.salary >= t1.losalary AND emp.salary <= t1.hisalary;-- 隐式查询 --
SELECT
emp.ename,
emp.salary,
salarygrade.grade
FROM emp,salarygrade
WHERE emp.salary >= salarygrade.losalary AND emp.salary <= salarygrade.hisalary;-- 显式查询 --
SELECT
emp.ename,
emp.salary,
salarygrade.grade
FROM emp
JOIN salarygrade ON emp.salary
BETWEEN salarygrade.losalary AND salarygrade.hisalary
-- 4.查询员工姓名、工资、职务名称、职务描述、部门名称、部门位置、工资等级
-- 显式查询 --
SELECT
emp.ename,
emp.salary,
job.jname,
job.description,
dept.dname,
dept.loc,
salarygrade.grade
FROM emp
INNER JOIN job ON emp.job_id=job.id
INNER JOIN dept ON emp.dept_id=dept.id
INNER JOIN salarygrade ON emp.salary BETWEEN salarygrade.losalary AND
salarygrade.hisalary;-- 隐式查询 --
SELECT
emp.ename,
emp.salary,
job.jname,
job.description,
dept.dname,
dept.loc,
salarygrade.grade
FROM emp,job,dept,salarygrade
WHERE emp.job_id=job.id AND emp.dept_id=dept.id AND emp.salary BETWEEN
salarygrade.losalary AND salarygrade.hisalary;
-- 5.查询出部门编号、部门名称、部门位置、部门人数
SELECT
dept.id,
dept.dname,
dept.loc,
COUNT(emp.id) AS '部门人数'
FROM dept
INNER JOIN emp ON emp.dept_id=dept.id
GROUP BY id;
-- 根据部门id分组查询每一个部门id和员工数
-- 聚合函数 --
SELECT dept_id, COUNT(*) FROM emp GROUP BY dept_id;
-- 嵌套查询 --
SELECT
dept.id,
dept.dname,
dept.loc,
t1.count
FROM
dept,(
SELECT
dept_id,
COUNT(*) COUNT
FROM
emp
GROUP BY
dept_id
) t1
WHERE
dept.id=t1.dept_id;
-- 6.查询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查询
-- 显式查询 --
SELECT
emp.ename,
t1.ename AS '直接上级领导'
FROM emp
INNER JOIN emp t1 ON emp.mgr=t1.id;-- 外连接查询 --
SELECT
emp.ename,
IFNULL(t1.ename,'无') AS '直接上级领导'
FROM emp
LEFT JOIN emp t1 ON emp.mgr=t1.id;
四张表的架构设计器：
