Question

我有一个表，我正在添加一个约束，所以如果PaymentType不同于'Check'，以确保CheckNumber为null。这是我的表：

create table RegistrationHeader(
    RegistrationNo numeric 
    ,BillingID varchar(30) unique not null
    ,RegistrationDate date not null
    ,PaymentType varchar(5) check (PaymentType = 'CC' or PaymentType = 'PO' or PaymentType = 'Check') not null
    ,CCNumber varchar(16) check(LEN(CCNumber) = 16 OR LEN(CCNumber) = 15)
    ,PONumber varchar(30)
    ,CheckNumber varchar(10) default null
    ,primary key(RegistrationNo)
    ,constraint CC_CCNumber_constr check(
        (PaymentType = 'CC' and CCNumber is not null)
        or
        (PaymentType != 'CC' and CCNumber is null)
    )
    ,constraint PO_PONumber_constr check(
        (PaymentType = 'PO' and (PONumber is not null or PONumber != ''))
        or
        (PaymentType != 'PO' and PONumber is null)
    )
);

所以，我试过了

,constraint CheckNumber_type_constr check((PaymentType = 'CC' or PaymentType = 'PO') and CheckNumber is null)

和

,constraint CheckNumber_type_constr check((PaymentType != 'Check') and CheckNumber is null)

两者都惨遭失败......

Answer 1

怎么样：

constraint CheckNumber_type_constr
    check ((PaymentType = 'Check') or (CheckNumber is null))

如果您想确保CheckNumber也不为null检查：

constraint CheckNumber_type_constr
    check ((PaymentType = 'Check' and CheckNumber is not null) or
           (PaymentType <> 'Check' and CheckNumber is null)
          )

SQL Server检查空值

1 个答案: