use StudentManageDB

 go

 --创建主键约束

 if exists(select * from sysobjects where name='pk_StudentId')

 alter table Students drop constraint pk_StudentId

 alter table Students add constraint pk_StudentId primary key(StudentId)

 --创建唯一约束

 if exists(select * from sysobjects where name='uq_StudentIdNo')

 alter table Students drop constraint uq_StudentIdNo

 alter table Students add constraint uq_StudentIdNo  unique(StudentIdNo)

 --创建检查约束

 if exists(select * from sysobjects where name='ck_Age')

 alter table Students drop constraint ck_Age

 alter table Students add constraint ck_Age  check(Age between 18 and 25)

 if exists(select * from sysobjects where name='ck_PhoneNumber')

 alter table Students drop constraint ck_PhoneNumber

 alter table Students add constraint ck_PhoneNumber  check(len(PhoneNumber)=11)

 update Students set PhoneNumber='' where StudentId=10000

 select * from Students

 --创建默认值

 if exists(select * from sysobjects where name='df_StudentAddress')

 alter table Students drop constraint df_StudentAddress

 alter table Students add constraint df_StudentAddress default('地址不详') for StudentAddress

 insert into Students (StudentName,Gender,Birthday,Age,StudentIdNo ,PhoneNumber,

 StudentAddress,ClassId)

 values('李小璐','女','1989-01-12',24,120229198901121315, '',default,1)

 insert into Students (StudentName,Gender,Birthday,Age,StudentIdNo ,PhoneNumber,

 ClassId)

 values('李小璐','女','1989-01-12',24,120229198901121316, '',1)

 --外键约束

 insert into StudentClass (ClassId,ClassName) values(1,'软件1班')

 if exists(select * from sysobjects where name='fk_ClassId')

 alter table Students drop constraint fk_ClassId

 alter table Students add constraint fk_ClassId  foreign key (ClassId) references StudentClass(ClassId)

 select * from studentClass