SQL Server中的表之间的约束,删除一个应该删除另一个

Question

我正在创建两个表RegistrationHeader和RegistrationDetail.我如何添加一个约束,当我删除RegistrationHeader表以自动删除RegistrationDetail表.

create table RegistrationHeader(
    RegistrationNo numeric
    ,BillingID varchar(30) not null
    ,RegistrationDate date not null
    ,PaymentType varchar check (PaymentType = 'CC' or PaymentType = 'PO' or PaymentType = 'Check') not null
    ,CCNumber numeric check(CCNumber >= 15 and CCNumber <=16)
    ,PONumber varchar(30)
    ,CheckNumber varchar(10)
    ,primary key(RegistrationNo)
    ,foreign key(BillingId) references Person(UserID) 
    ,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)
    )
    ,constraint CheckNumber_type_constr check(PaymentType != 'Check' and CheckNumber is null)
);

create table RegistrationDetail(
    RegistrationNo numeric
    ,LineNumber numeric
    ,CourseID numeric(10) not null
    ,AttendeeID varchar(30) not null
    primary key(RegistrationNo,LineNumber)
);

谢谢您的帮助!

Answer 1

你需要

1)在RegistrationHeader.RegistrationNo和之间建立外键关系RegistrationDetail.RegistrationNo

2)添加ON DELETE CASCADE到RegistrationDetail外键定义

我没有测试过这个,但我相信这应该是你在SQL Server中寻找的东西

ALTER TABLE RegistrationDetail
ADD CONSTRAINT FK_RegistrationHeader_RegistrationDetail_Cascade
FOREIGN KEY (RegistrationNo) REFERENCES RegistrationDetail (RegistrationNo) ON DELETE CASCADE