--方法一:创建表时直接指定主键和外键if object_id('tbChild') is not null drop table tbChildGOif object_id('tbMaster') is not null drop table tbMasterGO----创建主键表create table tbMaster(id int identity(1,1) PRIMARY KEY, name varchar(20) default 'xyz')----创建外键表create table tbChild(id int identity(1,1),pid int FOREIGN KEY REFERENCES tbMaster ( id ) ON DELETE CASCADE ON UPDATE CASCADE)GO----查看select * from tbMaster a left join tbChild b on a.id = b.pid----清除测试环境drop table tbChild,tbMasterGO----------------------------------------------------------------------------------方法二:先创建表,后添加主键或外键----创建测试表create table tbMaster(id int identity(1,1), name varchar(20) default 'xyz')create table tbChild(id int identity(1,1),pid int)GO----添加主键alter table tbMaster add constraint [PK_tbMaster] PRIMARY KEY(id)GO----添加外键alter table tbChild add constraint [FK_tbChild_tbMaster] FOREIGN KEY (pid) REFERENCES tbMaster(id) ON DELETE CASCADE ON UPDATE CASCADEGO----查看select * from tbMaster a left join tbChild b on a.id = b.pid
----清除测试环境drop table tbChild,tbMasterGO
