Select Inner Join Select in SQL

Question

Hi i Have a Select Inner Join Statement it seems ok but i got error. this is my query

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

I got this Error.

Only one expression can be specified in the select list when the subquery is not introduced with EXISTS.

Thank you in Advance.

Answer 1

You should include the column names and From keyword in the outer select statement

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

Actually you don't need to write the outer select, it can be rewritten as

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

The issue is at the beginning of your query,

Select( Select ....

Remove the initial "Select (" and retry the query. When you run a

Select (Select ..) 

the second select can only return one column (unless you concatenate the returned data).