SQL Server修改主、外键和约束

0.创建表

create table Users
(
Id int,
Name ),
Phone ),
Email ),
Role_Id uniqueidentifier
)
go
create table Roles
(
Id uniqueidentifier primary key,
Name ) not null
)

1.增加主键
alter table Users add constraint PK_Users_Id primary key(Id)

2.增加唯一约束
alter table Users add constraint UQ_Users_Name unique(Name)

3.增加检查约束
alter table Users add constraint CK_Users_Age check(Age>0 and Age<100)

4.增加非空约束
alter table Users add constraint NN_Users_Phone check(Phone is not null)

5.增加默认约束
alter table Users add constraint DF_Users_Email default('123456@qq.com') for Email

6.增加外键
alter table Users add constraint FK_Users_Roles_Id foreign key (Role_Id) references Roles(Id)

7.删除主外键或约束
alter table Users drop constraint FK_Users_Roles_Id