T-SQL查找其他数据库中缺少的项目

Question

I have 2 databases for 2 different system. EDI system and ERP System as below

I would like to know all the ProductId that are not in ErpOrderItem table for all the orders in EDI System Order table

A. EDI System

Order
----
1. OrderId
2. OrderDate

OrderItems
---------
1. OrderItemId

2. OrderId

3. ProductId

Order_Erp
------
1. OrderId
2. ErpDocNum


ERP System


ErpOrder
-------
1. ErpDocNum
2. DocEntry

ErpOrderItem
----
1. DocEntry
2. ProductId

For example , I would like to know all items that in OrderItems which are not available in ErpOrderItem for orders that linked by order key and ErpDocNum. These 2 systems are linked by ErpDocNum in Order_Erp table

I have tried as below but it's not giving the result I am after.

select * from edi.Orders ODR
INNER JOIN edi.Order_Erp ERDR ON  ODR.OrderId = ERDR.OrderId
INNER JOIN edi.OrdersItems ODRL ON ODR.OrderId = ODRL.OrderId
INNER JOIN ErpOrder ON ERDR.ErpDocNum = ErpOrder.ErpDocNum
INNER JOIN ErpOrderItem ON ErpOrder.DocEntry = ErpOrderItem.DocEntry
where ErpOrder.ProductId != ODRL.Productid collate SQL_Latin1_General_CP1_CI_AS

Answer 1

As per the table schema provided, the column mentioned in your on condition is wrong (ON ERDR.ErpOrderNumber = ErpOrder.DocNum )

SELECT * 
FROM edi.Orders ODR
  INNER JOIN edi.Order_Erp ERDR ON  ODR.OrderId = ERDR.OrderId
  INNER JOIN edi.OrdersItems ODRL ON ODR.OrderId = ODRL.OrderId
  INNER JOIN ErpOrder ON ERDR.ErpDocNum = ErpOrder.ErpDocNum
   INNER JOIN ErpOrderItem ON ErpOrder.DocEntry = ErpOrderItem.DocEntry
WHERE ErpOrder.ProductId != ODRL.Productid collate SQL_Latin1_General_CP1_CI_AS

Answer 2

If I understand your question correctly, what you are after is a list of all products that are in your EDI system but not in your ERP system? If that is all you want then this should be all you need to get those results. If I'm not correctly understanding your requirements it is usually helpful to provide an example of your tables and the expected results for clarification

SELECT DISTINCT ProductID
FROM edi.OrderItems AS OI
WHERE NOT EXISTS
(
    SELECT 1
    FROM ErpOrderItem AS EOI
    WHERE OI.ProductID = EOI.ProductID
)