使用SQL语句创建和删除约束

--添加主键约束   
Alter Table stuInfo   
Add Constraint  PK_stuNO primary Key(stuNo)   
---添加唯一约束   
Alter Table stuInfo   
Add Constraint UQ_stuID unique(stuID)   
---添加默认约束   
Alter Table stuInfo   
Add Constraint DF_stuAddress default(‘地址不详‘) for stuAddress   
---添加检查约束   
Alter Table stuInfo   
Add Constraint CK_stuAge check(stuAge between 15 and 40)   
---添加外键约束   
Alter Table stuMarks   
Add Constraint FK_stuNo foreign key(stuNo) references stuInfo(stuNo)  

Alter Table 表名   
Drop Constraint  约束名  

use stuDB   
go   
if exists(select * from Sysobjects where name = ‘stuInfo‘)   
drop table stuInfo   
go   
create table stuInfo   
(   
     stuName varchar(20) not null primary key(stuName)    
，stuID int not null unique(stuID)   
，stuAddress varchar(20) not null default(‘地址不详‘)   
，stuAge int not null check(stuAge between 15 and 40)   
)