USE db3;

CREATE TABLE IF NOT EXISTS music(
title VARCHAR(32)  COMMENT '专辑名',
alias VARCHAR(32) COMMENT '专辑别名',
image VARCHAR(64),
style VARCHAR(8),
`type` VARCHAR(4),
`medium` VARCHAR(4),
publish_time DATE,
publisher VARCHAR(16),
number TINYINT,
barcode BIGINT,
summary VARCHAR(1024),
artist VARCHAR(16),
id INT PRIMARY KEY AUTO_INCREMENT
);

CREATE TABLE IF NOT EXISTS song(
`name` VARCHAR(32),
`serial_number`  TINYINT,
id INT PRIMARY KEY AUTO_INCREMENT,
music_id INT 
);

CREATE TABLE IF NOT EXISTS review(
content VARCHAR(256),
rating TINYINT,
review_time DATETIME,
music_id INT,
user_id INT
);

CREATE TABLE IF NOT EXISTS `user`(
username VARCHAR(16) UNIQUE,
image VARCHAR(64),
signature VARCHAR(64),
nickname VARCHAR(16),
id INT PRIMARY KEY 
);

CREATE TABLE IF NOT EXISTS user_music(
id INT PRIMARY KEY AUTO_INCREMENT,
user_id INT,
music_id INT
);


ALTER TABLE song ADD CONSTRAINT fn_music_song FOREIGN KEY(music_id) REFERENCES music(id);
ALTER TABLE review ADD CONSTRAINT fn_music_review FOREIGN KEY(music_id) REFERENCES music(id);
ALTER TABLE review ADD CONSTRAINT fn_user_review FOREIGN KEY(user_id) REFERENCES `user`(id);
ALTER TABLE user_music ADD CONSTRAINT fn_key1 FOREIGN KEY(user_id) REFERENCES `user`(id);
ALTER TABLE user_music ADD CONSTRAINT fn_key2 FOREIGN KEY (music_id) REFERENCES music(id);




DROP TABLE IF EXISTS emp;
DROP TABLE IF EXISTS dept;
DROP TABLE IF EXISTS job;
DROP TABLE IF EXISTS salarygrade;

-- 部门表
CREATE TABLE dept (
  did INT PRIMARY KEY PRIMARY KEY, -- 部门id
  dname VARCHAR(50), -- 部门名称
  loc VARCHAR(50) -- 部门所在地
);

-- 职务表，职务名称，职务描述
CREATE TABLE job (
  id INT PRIMARY KEY,
  jname VARCHAR(20),
  description VARCHAR(50)
);

-- 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
);
ALTER TABLE emp  ADD CONSTRAINT emp_jobid_ref_job_id_fk FOREIGN KEY (job_id) REFERENCES job (id);
ALTER TABLE emp  ADD CONSTRAINT emp_deptid_ref_dept_id_fk FOREIGN KEY (dept_id) REFERENCES dept (did);



-- 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4个部门
INSERT INTO dept(did,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');

-- 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');


-- 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);


-- 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);



# 查询所有员工信息。查询员工编号，员工姓名，工资，职务名称，职务描述
SELECT emp.id,ename,salary,jname,description FROM emp LEFT JOIN job ON emp.`job_id`=job.`id` ;

# 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
SELECT t1.id,ename,salary,jname,description,dname,loc
FROM (SELECT emp.id id,ename,salary,jname,description,dept_id
 FROM emp LEFT JOIN job ON emp.`job_id`=job.`id`)t1 
 LEFT JOIN dept ON t1. dept_id =dept.`did`;

# 查询员工姓名，工资，工资等级
SELECT t2.ename,t2.salary,t1.grade
FROM salarygrade t1 ,emp t2 
WHERE t2.salary<t1.hisalary AND t2.salary>t1.losalary;

#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
SELECT ename,salary,jname,description,dname,loc,grade
FROM(SELECT t1.id,ename,salary,jname,description,dname,loc
FROM (SELECT emp.id id,ename,salary,jname,description,dept_id
 FROM emp LEFT JOIN job ON emp.`job_id`=job.`id`)t1 
 LEFT JOIN dept ON t1. dept_id =dept.`did`) t2,
 salarygrade WHERE t2.salary<=salarygrade.hisalary AND t2.salary>=salarygrade.losalary;
 
 
# 查询出部门编号、部门名称、部门位置、部门人数
SELECT dept.*,t1.num '部门人数'
FROM dept LEFT JOIN 
(SELECT dept_id,COUNT(*) num FROM emp GROUP BY dept_id) t1
ON dept.`did`=t1.dept_id;

 
 
# 事务操作
DROP TABLE IF EXISTS account;

-- 创建账户表
CREATE TABLE account(
	id INT PRIMARY KEY AUTO_INCREMENT,
	NAME VARCHAR(10),
	money DOUBLE(10,2)
);

-- 添加数据
INSERT INTO account(NAME,money) VALUES('张三',1000),('李四',1000);
 
 
 -- 转账操作
 -- 1.查询李四的余额
 SELECT * FROM account;
 -- 2.李四金额 -500
 UPDATE account SET money =money -500 WHERE NAME='李四';
 出错了...
 -- 3.张三金额 +500
 UPDATE account SET money =money +500 WHERE NAME ='张三';
 
 
 -- 带事务的转账操作

 -- 1.查询李四的余额
 SELECT * FROM account;
 
  -- 开启事务
 BEGIN;
 -- 2.李四金额 -500
 UPDATE account SET money =money -500 WHERE NAME='李四';
 出错了...
 
 -- 3.张三金额 +500
 UPDATE account SET money =money +500 WHERE NAME ='张三';


-- 提交数据
COMMIT;

 -- 回滚事务
 ROLLBACK;
 
 
 SELECT @@autocommit;
 # 查询到的结果是1 则表示自动提交，结果是0表示手动提交。
 # 当然也可以通过下面语句修改提交方式
 SET @@autocommit = 0;