SQL 级联删除与级联更新的技巧
发布时间：2021-12-03 20:28:23 所属栏目：教程 来源：互联网
导读：复制代码 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 (Cou
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复制代码 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  （编辑：济南站长网） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |
