外键约束

 

 

 

 

 

 

CREATE TABLE USER (
    id INT PRIMARY KEY AUTO_INCREMENT,  -- id
    name VARCHAR(20)                                        -- 姓名
);

INSERT INTO USER VALUES (NULL,'张三'),(NULL,'李四');

CREATE TABLE orderlist(
    id INT PRIMARY KEY AUTO_INCREMENT,  -- id
    number VARCHAR(20),                                    -- 订单编号
    uid INT,                                                        -- 外键列
    CONSTRAINT ou_fk1 FOREIGN KEY (uid) REFERENCES USER(id)
);

INSERT INTO orderlist VALUES (NULL,'hw1',1),(NULL,'hw2',1),(NULL,'hw3',2),(NULL,'hw4',2);