在SQL中选择内部联接选择

Question

嗨，我有一个选择内部加入声明，这似乎还可以，但我出错了。 这是我的查询

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

我收到此错误。

如果未使用EXISTS引入子查询，则只能在选择列表中指定一个表达式。

先感谢您。

Answer 1

您应该在外部select语句中包含列名和From关键字

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

实际上，您不需要编写外部选择，可以将其重写为

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

问题出在查询的开头，

Select( Select ....

删除初始的“选择（”，然后重试查询。当您运行

Select (Select ..) 

第二个选择只能返回一列（除非您串联返回的数据）。