Home > Database > Mysql Tutorial > SQL 级联删除与级联更新的方法

SQL 级联删除与级联更新的方法

WBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWB
Release: 2016-06-07 17:54:55
Original
1516 people have browsed it

SQL 级联删除与级联更新的方法,需要的朋友可以参考一下

代码如下:
on delete cascade

当你更新或删除主键表时,那么外键表也会跟随一起更新或删除,需要在建表时设置级联属性

CREATE TABLE Countries(CountryId INT PRIMARY KEY)
INSERT INTO Countries (CountryId) VALUES (1)
INSERT INTO Countries (CountryId) VALUES (2)
INSERT INTO Countries (CountryId) VALUES (3)

CREATE TABLE Cities( CityId INT PRIMARY KEY ,CountryId INT REFERENCES Countries ON DELETE CASCADE);
INSERT INTO Cities VALUES(1,1)
INSERT INTO Cities VALUES(2,1)
INSERT INTO Cities VALUES(3,2)

CREATE TABLE Buyers(CustomerId INT PRIMARY KEY ,CityId INT REFERENCES Cities ON DELETE CASCADE);
INSERT INTO Buyers VALUES(1,1),
INSERT INTO Buyers VALUES(2,1)
INSERT INTO Buyers VALUES(3,2)

此外还有级联更新
on update cascade

Related labels:
sql
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Latest Issues
sql file
From 1970-01-01 08:00:00
0
0
0
php - Overhead of prepare vs sql?
From 1970-01-01 08:00:00
0
0
0
Print sql statement
From 1970-01-01 08:00:00
0
0
0
Pass array to SQL insert query using PHP
From 1970-01-01 08:00:00
0
0
0
sql optimization or
From 1970-01-01 08:00:00
0
0
0
Popular Tutorials
More>
Latest Downloads
More>
Web Effects
Website Source Code
Website Materials
Front End Template