外键约束

CREATE TABLE dept11(

id int primary key auto_increment,

dep_name varchar(20),

addr varchar(20)

);

CREATE TABLE emp11(

id int primary key auto_increment,

name varchar(20),

age int,

dep_id int,

-- 添加外键dep_id,关联dept表的id主键

CONSTRAINT fk_emp11_dept11 FOREIGN KEY(dep_id) REFERENCES dept11(id)

);--fk是随意字符串

INSERT INTO dept11(dep_name,addr) values('研发部','广州'),('销售部','深圳');

INSERT INTO emp11(NAME,age,dep_id)values

('张三',20,1),

('李四',20,1),

('王五',20,1),

('赵六',20,2),

('孙七',22,2),

('周八',18,2);

select * from emp11;

select * from dept11;