在SQL中選擇內部聯接選擇

Question

嗨，我有一個選擇內部加入聲明，這似乎還可以，但我出錯了。 這是我的查詢

ALTER PROCEDURE [dbo].[POBalance]  @PONumber nvarchar(50)
AS BEGIN
Select( 
Select 
    A.Description,
    C.qty as POqty,
    B.QtyDelivered as PDQty, 
    case when A.partialflag ='false' 
    then '0'
    else
    A.qty  end as Balance,
    A.Unit,
    A.Unitprice,
    A.Partialflag 
from tblPOdetails as A

Inner Join  ( SELECT  id, SUM(Qty) AS QtyDelivered
                                    FROM         dbo.tblPDdetails
                                    WHERE     (PONo = @PONumber)
                                    GROUP BY id)as B On A.id = B.id   
Inner Join tblpodetailshistory as C on A.id =C.id

where A.PONo = @PONumber)
END

我收到此錯誤。

如果未使用EXISTS引入子查詢，則只能在選擇列表中指定一個表達式。

先感謝您。

Answer 1

您應該在外部select語句中包含列名和From關鍵字

ALTER PROCEDURE [dbo].[POBalance]  @PONumber nvarchar(50)
AS BEGIN
Select Description, POqty, PDQty, Balance, Unit, Unitprice, Partialflag  from ( 
Select 
    A.Description,
    C.qty as POqty,
    B.QtyDelivered as PDQty, 
    case when A.partialflag ='false' 
    then '0'
    else
    A.qty  end as Balance,
    A.Unit,
    A.Unitprice,
    A.Partialflag 
from tblPOdetails as A

Inner Join  ( SELECT  id, SUM(Qty) AS QtyDelivered
                                    FROM         dbo.tblPDdetails
                                    WHERE     (PONo = @PONumber)
                                    GROUP BY id)as B On A.id = B.id   
Inner Join tblpodetailshistory as C on A.id =C.id

where A.PONo = @PONumber)
END

實際上，您不需要編寫外部選擇，可以將其重寫為

ALTER PROCEDURE [dbo].[POBalance]  @PONumber nvarchar(50)
AS BEGIN

Select 
    A.Description,
    C.qty as POqty,
    B.QtyDelivered as PDQty, 
    case when A.partialflag ='false' 
    then '0'
    else
    A.qty  end as Balance,
    A.Unit,
    A.Unitprice,
    A.Partialflag 
from tblPOdetails as A

Inner Join  ( SELECT  id, SUM(Qty) AS QtyDelivered
                                    FROM         dbo.tblPDdetails
                                    WHERE     (PONo = @PONumber)
                                    GROUP BY id)as B On A.id = B.id   
Inner Join tblpodetailshistory as C on A.id =C.id

where A.PONo = @PONumber
END

Answer 2

問題出在查詢的開頭，

Select( Select ....

刪除初始的“選擇（”，然后重試查詢。當您運行

Select (Select ..) 

第二個選擇只能返回一列（除非您串聯返回的數據）。