內部聯接和集團多個表到一行

Question

我使用MSSQL Server和我想INNER JOIN和GROUP從多個表中的數據。但我得到這個錯誤：

Column 'MyDB.dbo.USER.EmployeeID' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause. 

假設我有表如下：

表Stock

StockID  StockName 
    --------------------------- 
    1    StockOne 
    2    StockTwo 

表用戶

EmployeeID EmployeeName 
    --------------------------- 
    A001   ABC 
    A002   ABCD 

表徵用

RequisitionID RequestDetailsID RequestNumber EmployeeID 
    --------------------------------------------------------------- 
    1    1     RN001   A001 
    2    2     RN001   A001 
    3    3     RN002   A002 
    4    4     RN003   A001 

表REQUISITION_DETAILS

RequestDetailsID EmployeeID StockID 
    ------------------------------------------ 
    1     A001   1 
    2     A001   2 
    3     A002   1 
    4     A001   2 

這是我SQL語法：

SELECT * 

    FROM [MyDB].[dbo].[USER] A 

    INNER JOIN 
    [MyDB].[dbo].[REQUISITION] B 
    ON 
    B.EmployeeID = A.EmployeeID 

    INNER JOIN 
    [MyDB].[dbo].[REQUISITION_DETAILS] C 
    ON 
    C.RequestDetailsID = B.RequestDetailsID 

    INNER JOIN [MyDB].[dbo].[STOCK] D 
    ON 
    D.StockID = C.StockID 

    WHERE EmployeeID = '$EpID' 
    GROUP BY B.RequestNumber 

預期輸出

RequestNumber RequestDetailsID EmployeeID EmployeeName  StockID 
    ------------------------------------------------------------------------------ 
    RN001   1, 2    A001   ABC    1, 2 
    RN002   3     A002   ABCD    1 
    RN003   4     A001   ABC    2 

Answer 1

這是有幾個原因一個棘手的查詢。首先，SQL Server有一個相當痛苦的做聚合字符串連接的方式。然後，你有連接不同表中的請求號碼和僱員的問題。

從我可以告訴，你只需要兩個表，requisition和requisition_details。下面的查詢應接近你所需要的：

select distinct r.RequestNumber, r.EmployeeId, 
     stuff((select ', ' + cast(rd.RequestDetailsId as varchar(255)) 
       from requisition r2 join 
        requisition_details rd 
        on r2.RequestDetailsID = rd.RequestDetailsID 
       where r2.RequestNumber = r.RequestNumber and r2.EmployeeId = r.EmployeeId 
       for xml path ('') 
      ), 1, 2, '') as RequestDetailIds, 
     stuff((select ', ' + cast(rd.StockId as varchar(255)) 
       from requisition r2 join 
        requisition_details rd 
        on r2.RequestDetailsID = rd.RequestDetailsID 
       where r2.RequestNumber = r.RequestNumber and r2.EmployeeId = r.EmployeeId 
       for xml path ('') 
      ), 1, 2, '') as StockIds 
from requisition r 

編輯：

要插入新行，我只想用：

 stuff((select ' 
' + cast(rd.RequestDetailsId as varchar(255)) 
       from requisition r2 join 
        requisition_details rd 
        on r2.RequestDetailsID = rd.RequestDetailsID 
       where r2.RequestNumber = r.RequestNumber and r2.EmployeeId = r.EmployeeId 
       for xml path ('') 
      ), 1, 2, '') as RequestDetailIds,