Question

我有两张桌子。

采购：

PurchaseId
SenderId
ReceiverId

客户：

Customerid（小学唯一）
CUSID（非主要 - 非唯一 - 允许空）
FirsName
LastName

我想通过customers表中的用户名和姓氏来购买所有报告。我无法建立任何关系。我的所有代码都会给我错误或返回错误的结果。请帮帮我。（接收者和发送者的值在客户表中等于CUSID）关系是错误的：因为我不能创建任何主键，因为我的字段是允许为空。

(select (tbl_Customers.FirstName + '-' +  tbl_Customers.LastName) as receiver
FROM         tbl_PurchaseForms
INNER JOIN
tbl_Customers ON tbl_PurchaseForms.ReceiverUId = tbl_Customers.CUSID) 
or
(select (tbl_Customers.FirstName + '-' +  tbl_Customers.LastName) as sender
FROM         tbl_PurchaseForms
INNER JOIN
tbl_Customers ON tbl_PurchaseForms.SenderUId = tbl_Customers.CUSID)

Answer 1

我确实对你的问题感到有点困惑，但听起来你正试图归还所有收到或从你的购买表中发送东西的客户，链接你的cusid字段？

如果是这样的话，这样的事情应该有用（如果你需要区分发件人和接收者，我已经包含了一个名为购买类型的额外栏目）：

SELECT 
    'Sender' as PurchaseType, 
    C.FirstName, 
    C.LastName
FROM Customers C 
    JOIN Purchase P ON C.CUSID  = P.SenderId
UNION 
SELECT 
    'Receiver' as PurchaseType, 
    C.FirstName, 
    C.LastName
FROM Customers C 
    JOIN Purchase P ON C.CUSID  = P.ReceiverId

祝你好运。

Answer 2

Select p.*
,(Select  c.FirstName + '-' +  c.LastName  from customers c where c.CUSID  = P.ReceiverId) as  receiver
,(Select  c.FirstName + '-' +  c.LastName  from customers c where c.CUSID  = P.SenderId) as  Sender
from purchase p

虽然购买应设计为启用此

Select p.*
,(Select  c.FirstName + '-' +  c.LastName  from customers c where c.Customerid  = P.ReceiverId) as  receiver
,(Select  c.FirstName + '-' +  c.LastName  from customers c where c.Customerid  = P.SenderId) as  Sender
from purchase p

可空的主键

2 个答案: