SQL Server数据库操作（二）

            use
             studentmanagedb

            go
            --
            添加约束,创建主键约束
            if
            exists(select*from sysobjects where name=‘pk_StudentId‘)
altertable Students dropconstraint pk_StudentId

altertable Students addconstraint pk_StudentId primarykey(StudentId)

--添加约束,创建唯一约束ifexists(select*from sysobjects where name=‘uq_StudentIdNo‘)
altertable Students dropconstraint uq_StudentIdNo

altertable Students addconstraint uq_StudentIdNo unique(StudentIdNo)

            --
            添加约束,创建检查约束
            if
            exists(select*from sysobjects where name=‘ck_Age‘)
altertable Students dropconstraint ck_Age

altertable Students addconstraint ck_Age check(Age between18and26)

ifexists(select*from sysobjects where name=‘ck_PhoneNumber‘)
altertable Students dropconstraint ck_PhoneNumber

altertable Students addconstraint ck_PhoneNumber check(len(PhoneNumber)=11)

            --
            创建外键约束
            if
            exists(select*from sysobjects where name=‘fk_ClassId‘)
altertable Students dropconstraint fk_ClassId

altertable Students addconstraint fk_ClassId foreignkey(ClassId) references StudentClass(ClassId)