摘要：
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 I 阅读全文