SQL Select within Sub Query - sql-server

Question

Hi My query is as follows, and contains a subquery within it:
ALTER PROCEDURE [dbo].[POBalance] #PONumber NVARCHAR(50)
AS
BEGIN
SELECT CASE
WHEN X.STATUS = 'False'
THEN ( SELECT A.Description
,C.qty AS POqty
,B.Qty 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 tblPDdetails AS B ON A.id = B.id
INNER JOIN tblpodetailshistory AS C ON A.id = C.id
WHERE A.PONo = #PONumber
)
ELSE ( SELECT A.Description
,C.qty AS POqty
,B.Qty AS PDQty
,C.qty AS Balance
,A.Unit
,A.Unitprice
,A.Partialflag
FROM tblPOdetails AS A
INNER JOIN tblPDdetails AS B ON A.id = B.id
INNER JOIN tblpodetailshistory AS C ON A.id = C.id
WHERE A.PONo = #PONumber)
END
FROM tblPOHeader AS X
WHERE x.PONo = #PONumber
END
The error i get is :
Only one expression can be specified in the select list when the subquery is not
introduced with EXISTS.
What is wrong with my query..it seems my sub query is OK.
THanks in Advance

Answer 1

You can not select table in case clausule. You can do it just like that (I didn't test it):
SELECT A.Description
,C.qty AS POqty
,B.Qty 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 tblPDdetails AS B ON A.id = B.id
INNER JOIN tblpodetailshistory AS C ON A.id = C.id
INNER JOIN tblPOHeader X ON x.PONo = A.PONo
WHERE A.PONo = #PONumber and X.STATUS = 'False'
UNION ALL
SELECT A.Description
,C.qty AS POqty
,B.Qty AS PDQty
,C.qty AS Balance
,A.Unit
,A.Unitprice
,A.Partialflag
FROM tblPOdetails AS A
INNER JOIN tblPDdetails AS B ON A.id = B.id
INNER JOIN tblpodetailshistory AS C ON A.id = C.id
INNER JOIN tblPOHeader X ON x.PONo = A.PONo
WHERE A.PONo = #PONumber and X.STATUS <> 'False'
But I think tah X.STATUS is bit - if yes you should do it just like that:
SELECT A.Description
,C.qty AS POqty
,B.Qty 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 tblPDdetails AS B ON A.id = B.id
INNER JOIN tblpodetailshistory AS C ON A.id = C.id
INNER JOIN tblPOHeader X ON x.PONo = A.PONo
WHERE A.PONo = #PONumber and X.STATUS = 0
UNION ALL
SELECT A.Description
,C.qty AS POqty
,B.Qty AS PDQty
,C.qty AS Balance
,A.Unit
,A.Unitprice
,A.Partialflag
FROM tblPOdetails AS A
INNER JOIN tblPDdetails AS B ON A.id = B.id
INNER JOIN tblpodetailshistory AS C ON A.id = C.id
INNER JOIN tblPOHeader X ON x.PONo = A.PONo
WHERE A.PONo = #PONumber and X.STATUS <> 0

Answer 2

Are you actually looking for this?
ALTER PROCEDURE [dbo].[POBalance] #PONumber NVARCHAR(50)
AS
BEGIN
DECLARE #Status NVARCHAR(MAX)
SELECT #Status = X.STATUS
FROM tblPOHeader AS X WHEREx.PONo = #PONumber
IF #Status = 'False'
BEGIN
SELECT A.Description
,C.qty AS POqty
,B.Qty 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 tblPDdetails AS B ON A.id = B.id
INNER JOIN tblpodetailshistory AS C ON A.id = C.id
WHERE A.PONo = #PONumber
END
ELSE
BEGIN
SELECT A.Description
,C.qty AS POqty
,B.Qty AS PDQty
,C.qty AS Balance
,A.Unit
,A.Unitprice
,A.Partialflag
FROM tblPOdetails AS A
INNER JOIN tblPDdetails AS B ON A.id = B.id
INNER JOIN tblpodetailshistory AS C ON A.id = C.id
WHERE A.PONo = #PONumber
END
END
This code will store and then check the value of #Status and based on if the value is False or not then it will return the result set of one of the queries.

Answer 3

You cannot select multiple fields for one expression.Your alias makes it more visible.You select more than one value and give only one alias name!!
Please refer this
Only One Expression in case
And this one too
Another one here

Answer 4

When
select * from tblPOHeader where PONo = #PONumber
returns only one row you can do something like that
declare #STATUS nvarchar(200) = ( select STATUS from tblPOHeader where PONo = #PONumber)
if #STATUS = 'False'
SELECT A.Description
,C.qty AS POqty
,B.Qty 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 tblPDdetails AS B ON A.id = B.id
INNER JOIN tblpodetailshistory AS C ON A.id = C.id
WHERE A.PONo = #PONumber
ELSE
SELECT A.Description
,C.qty AS POqty
,B.Qty AS PDQty
,C.qty AS Balance
,A.Unit
,A.Unitprice
,A.Partialflag
FROM tblPOdetails AS A
INNER JOIN tblPDdetails AS B ON A.id = B.id
INNER JOIN tblpodetailshistory AS C ON A.id = C.id
WHERE A.PONo = #PONumber