mysql级联删除

一个building对应多个rooms，building删除----级联删除相关的rooms

第一步， 创建buildings表，如下创建语句：

USE testdb;
CREATE TABLE buildings (
    building_no INT PRIMARY KEY AUTO_INCREMENT,
    building_name VARCHAR(255) NOT NULL,
    address VARCHAR(255) NOT NULL
)ENGINE=InnoDB DEFAULT CHARSET=utf8;

第二步， 创建rooms表，如下创建语句：

USE testdb;
CREATE TABLE rooms (
    room_no INT PRIMARY KEY AUTO_INCREMENT,
    room_name VARCHAR(255) NOT NULL,
    building_no INT NOT NULL,
    FOREIGN KEY (building_no)
        REFERENCES buildings (building_no)
        ON DELETE CASCADE
)ENGINE=InnoDB DEFAULT CHARSET=utf8;