sql中为表加约束的sql语句

 --为表userinfo的loginName列加唯一约束
alter table userinfo
add constraint UQ_loginName unique(loginName)

--为表userinfo的age列添加检查约束
alter table userinfo
add constraint CK_age check(age between 0 and 100)

--为表userinfo的address列添加默认约束
alter table userinfo
add constraint DF_address default('地址不详') for address

--为表userinfo的classId添加对应classinfo表的classId主键的外键
alter table userinfo
add constraint PK_classId foreign key(classId) references classinfo(classId)