Question

mysql怎么设置级联删除

Answer 1

这个在建表的时候就可以指定了
CREATE TABLE buildings (
building_no INT PRIMARY KEY AUTO_INCREMENT,
building_name VARCHAR(255) NOT NULL,
address VARCHAR(255) NOT NULL
);
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
);
当执行
DELETE FROM buildings
WHERE
building_no = 2;的时候，rooms表中的building_no =2的记录都会被删掉。

Answer 2

通过触发器来级联删除：
具体的触发器代码如下：
Create TRIGGER [dbo].[DeleteRelatedProducts] ON [dbo].[ProductCategory]
AFTER DELETE
AS
BEGIN
SET NOCOUNT ON;
delete from [dbo].[product] where categoryId in
(
select id from deleted
)
END