sqlite3中的外键问题

Question

我收到一个错误“外键定义中的未知列“ CustID”” 和“没有这样的表：serviceticket”

有人可以帮助我吗？

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Answer 1

下面的代码将起作用。

这具有三个更改，而不是使用FOREIGN KEY (CustID) REFERENCES customer (CustID)，这需要定义 serviceticket 表中的 CustID 列； CustID REFERENCES customer (CustID)，这将定义CustID列并设置外键约束。

第二个更改将 098636 替换为 170362 ，这将导致外键约束冲突，该值是 CustID 中存在的值客户表的列。

例如：-

这有效（在正确定义表之后）：-

    insert into serviceticket (TicketID, WatchID, CustID, DateRecieved, DateReturned, ExpectedDelivery, COMMENTS, DateReturned)
    values (6745, 87463, '170362', 124319, 362836, 683743, 'Nothing to say', 583728)
> Affected rows: 1
> Time: 0.082s

（根据消息）这将失败

insert into serviceticket (TicketID, WatchID, CustID, DateRecieved, DateReturned, ExpectedDelivery, COMMENTS, DateReturned)
values (6745, 87463, 098636, 124319, 362836, 683743, 'Nothing to say', 583728)
> FOREIGN KEY constraint failed
> Time: 0s

第三个更改是交换删除表的顺序。

工作代码

drop table if exists serviceticket; -- <<<<<<<<<< if not coding ON DELETE CASCADE the children have to be deleted first (so moved before dropping customer table) 
drop table if exists customer;


PRAGMA foreign_keys = ON; 

create table customer (CustID char(6) not null primary key UNIQUE, 
    CustNAME TEXT, 
    STREET TEXT, 
    CITY TEXT, 
    ZIP INT(5),
    EMAIL VARCHAR, 
    PHONENUMBER INT(10)
    );

create table serviceticket (TicketID char(4) not null primary key, 
    TicketNO char(5), 
    WatchID char(6), 
    DateRecieved char(6), 
    ExpectedDelivery char(6), 
    COMMENTS text, 
    DateReturned char(6),
    CustID REFERENCES customer (CustID) -- <<<<<<<<<< defines the column and foreign key
    );

insert into customer (CustID, CustNAME, STREET, CITY, ZIP, PHONENUMBER, EMAIL) 
    values (170362, 'James', 'Vvegen', 'New York', 12345, 8170710520, 'brt92@outlook.com');

insert into serviceticket (TicketID, WatchID, CustID, DateRecieved, DateReturned, ExpectedDelivery, COMMENTS, DateReturned)
    values (6745, 87463, 
        '170362', -- <<<<<<<<<< MUST match a value in CustID column of the customer table (changed to work)
        124319, 362836, 683743, 'Nothing to say', 583728);

其他

您不妨考虑使用（或其变体）：-

CustID REFERENCES customer (CustID) ON DELETE CASCADE ON UPDATE CASCADE

4.3. ON DELETE and ON UPDATE Actions

Answer 2

您没有在定义外键之前定义CustID：

create table serviceticket (TicketID char(4) not null primary key, 
    TicketNO char(5), 
    WatchID char(6), 
    DateRecieved char(6), 
    ExpectedDelivery char(6), 
    COMMENTS text, 
    DateReturned char(6),
    CustID char(6),
    FOREIGN KEY (CustID) REFERENCES customer(CustID)
    );