部门表

CREATE TABLE dept( deptno INT PRIMARY KEY, '部门编号' dname VARCHAR(14) , '部门名称' loc VARCHAR(13) '部门地址' ); #部门表数据 INSERT INTO dept VALUES (10,'财务部','北京'),(20,'市场部','上海'), (30,'销售部','广州'),(40,'运营部','深圳');

员工表

CREATE TABLE emp( empno INT PRIMARY KEY, '员工编号' ename VARCHAR(10), '员工姓名' job VARCHAR(20), '员工工作' mgr INT, '员工直属领导编号' hiredate DATE, '入职时间' sal DOUBLE, '工资' comm DOUBLE, '奖金' deptno INT '对应dept表的外键' );

添加 部门 和 员工 之间的主外键关系

ALTER TABLE emp ADD CONSTRAINT FOREIGN KEY emp(deptno) REFERENCES dept (deptno);

INSERT INTO emp VALUES(7369,'smith','保洁工作',7902,'1980-12-17',800,NULL,20); INSERT INTO emp VALUES(7499,'allen','销售工作',7698,'1981-02-20',1600,300,30); INSERT INTO emp VALUES(7521,'ward','销售工作',7698,'1981-02-22',1250,500,30); INSERT INTO emp VALUES(7566,'jones','管理工作',7839,'1981-04-02',2975,NULL,20); INSERT INTO emp VALUES(7654,'martin','销售工作',7698,'1981-09-28',1250,1400,30); INSERT INTO emp VALUES(7698,'blake','管理工作',7839,'1981-05-01',2850,NULL,30); INSERT INTO emp VALUES(7782,'clark','管理工作',7839,'1981-06-09',2450,NULL,10); INSERT INTO emp VALUES(7788,'scott','策划工作',7566,'1987-07-03',3000,NULL,20); INSERT INTO emp VALUES(7839,'king','大BOSS',NULL,'1981-11-17',5000,NULL,10); INSERT INTO emp VALUES(7844,'turner','销售工作',7698,'1981-09-08',1500,0,30); INSERT INTO emp VALUES(7876,'adams','保洁工作',7788,'1987-07-13',1100,NULL,20); INSERT INTO emp VALUES(7900,'james','保洁工作',7698,'1981-12-03',950,NULL,30); INSERT INTO emp VALUES(7902,'ford','策划工作',7566,'1981-12-03',3000,NULL,20); INSERT INTO emp VALUES(7934,'miller','保洁工作',7782,'1981-01-23',1300,NULL,10);

工资等级表

CREATE TABLE salgrade( grade INT, '等级' losal DOUBLE, '最低工资' hisal DOUBLE '最高工资' );

INSERT INTO salgrade VALUES (1,700,1200),(2,1201,1400), (3,1401,2000),(4,2001,3000),(5,3001,9999);

返回员工姓名和该员工领导的姓名。

数据库 SELECT e.ename, m.ename FROM emp e LEFT JOIN emp m ON e.mgr = m.empno;