如果在客户项目表中提到客户，如何选择客户项目。 [英] How to select item of customer , if customer is mentioned in customer item table .?

问题描述

我有两个表首先是项目主表（Icode，ItemName，UOM）和第二个客户项目表（CICode，CItemName，UOM，CustomerID，Icode），现在我想要当我在第二个表中定义客户然后第二个表项是显示，如果在第二个表中没有提到那么从第一个表中选择项目。



我尝试了什么：

i have two table first is item master table(Icode,ItemName,UOM) and second customer item tabel(CICode,CItemName,UOM,CustomerID,Icode), Now i want when i define customer in second talbe then second table item is display, if do not mentioned in second table then item pick from first table.

What I have tried:

select ItemMasterFile.Descriptionitem,Customeritem.Citem ,customeritem.CIname,Customer.CustomerName
from ItemMasterFile left Join customeritem on ItemMasterFile.CodeItem=customeritem.Citem
left join Customer on Customer.CustomerID=Customeritem.CustomerID


if Customer exist 
   join with Customeritem 
else 
  Join with ItemMasterFile

推荐答案

在这里查看LEFT JOIN示例： SQL LEFT JOIN关键字 [ ^ ]

在您的情况下，查询应如下所示：

Take a look a the LEFT JOIN example here: SQL LEFT JOIN Keyword[^]
In your case the query should look like this:

SELECT Customers.CustomerName, Orders.OrderID
FROM Customers
LEFT JOIN Orders
ON Customers.CustomerID=Orders.CustomerID
WHERE OrderID IS NOT NULL
ORDER BY Customers.CustomerName;

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