T-SQL split result into two rows - sql-server

Question

I'm building a customer statement report and have the below query.
SELECT TOP (100) PERCENT dbo.vCustomerTransactions.datTrans AS InvDate
,dbo.vCustomerTransactions.strDocRef
,SUM(dbo.vCustomerTransactions.intAmountTax) AS Debit
,ISNULL(dbo.Cashbook.strTransRef, 'None') AS strTransRef
,ISNULL(SUM(dbo.Cashbook.intAmount), 0) AS Credit
,ISNULL(dbo.Cashbook.datCaptured, 0) AS PaymentDate
FROM dbo.vCustomerTransactions
LEFT OUTER JOIN dbo.Cashbook ON dbo.vCustomerTransactions.strDocID = dbo.Cashbook.strDocID
WHERE dbo.vCustomerTransactions.datTrans BETWEEN '2020-02-01 00:00:00'
AND '2020-03-18 00:00:00'
AND dbo.vCustomerTransactions.strTransType IN ('INV')
GROUP BY dbo.vCustomerTransactions.strDocRef
,dbo.Cashbook.strTransRef
,dbo.vCustomerTransactions.datTrans
,dbo.Cashbook.datCaptured
ORDER BY dbo.Cashbook.strTransRef DESC
,dbo.vCustomerTransactions.datTrans
The data is returned as follows.
"2020-02-29 00:00:00" "INV0034004" "1236.7675" "RCPT0007790" "1236.77" "2020-03-10 00:00:00"
What i need to do for that report is split that 1 row into two result rows, as follows
"2020-02-29 00:00:00" "INV0034004" "1236.7675" "0.00"
"2020-03-10 00:00:00" "RCPT0007790" "0.00" "1236.77"
So its splitting the data into debts and credits. I have no idea how to achieve this, please could someone point me in the right direction.
Many Thanks.

Answer 1

I'm making some guesses here, especially in regards that if Credit or Debit has a value of 0 you don't want the row, however using VALUES would likely be better here. It would certainly avoid the overhead of 2 scans of the tables, and the costly UNION (rather than UNION ALL):
WITH CTE AS(
--3 part naming for columns is being removed from SQL Server,. Don't use it.
SELECT --Removed Top, as pointless
CT.datTrans AS InvDate,
CT.strDocRef,
SUM(CT.intAmountTax) AS Debit,
ISNULL(Cb.strTransRef, 'None') AS strTransRef,
ISNULL(SUM(Cb.intAmount), 0) AS Credit,
ISNULL(Cb.datCaptured, 0) AS PaymentDate
FROM dbo.vCustomerTransactions CT
LEFT OUTER JOIN dbo.Cashbook Cb ON CT.strDocID = Cb.strDocID
WHERE CT.datTrans BETWEEN '2020-02-01T00:00:00' AND '2020-03-18T00:00:00'
AND CT.strTransType IN ('INV')
GROUP BY CT.strDocRef,
Cb.strTransRef,
CT.datTrans,
Cb.datCaptured)
SELECT C.InvDate,
C.strDocRef,
V.Debit,
C.strTransRef,
V.Credit,
C.PaymentDate
FROM CTE C
CROSS APPLY (VALUES (0, C.Debit),
(C.Credit, 0)) V (Credit, Debit)
WHERE NOT(V.Debit = 0 AND V.Credit = 0)
ORDER BY C.strTransRef DESC,
C.InvDate;

Answer 2

My approach would be to take the original query and make it into a Common Table Expression (or a temporary table if you want to do it the old school way). And then do two queries - one for credits and one for debits - off of that resultset and UNION them together. Something like this:
WITH cteMain AS (
SELECT TOP (100) PERCENT dbo.vCustomerTransactions.datTrans AS InvDate
,dbo.vCustomerTransactions.strDocRef
,SUM(dbo.vCustomerTransactions.intAmountTax) AS Debit
,ISNULL(dbo.Cashbook.strTransRef, 'None') AS strTransRef
,ISNULL(SUM(dbo.Cashbook.intAmount), 0) AS Credit
,ISNULL(dbo.Cashbook.datCaptured, 0) AS PaymentDate
FROM dbo.vCustomerTransactions
LEFT OUTER JOIN dbo.Cashbook ON dbo.vCustomerTransactions.strDocID = dbo.Cashbook.strDocID
WHERE dbo.vCustomerTransactions.datTrans BETWEEN '2020-02-01 00:00:00'
AND '2020-03-18 00:00:00'
AND dbo.vCustomerTransactions.strTransType IN ('INV')
GROUP BY dbo.vCustomerTransactions.strDocRef
,dbo.Cashbook.strTransRef
,dbo.vCustomerTransactions.datTrans
,dbo.Cashbook.datCaptured
)
SELECT InvDate AS TheDate, strDocRef AS TheRef, Debit, 0.0 AS Credit
FROM cteMain
UNION
SELECT PaymentDate AS TheDate, strTransRef AS TheRef, 0.00 AS Debit, Credit
FROM cteMain
You might also need a WHERE Debit > 0.00 and WHERE Credit > 0.0 in those two SELECT statements, to only pick up the credits/debits that have values, depending on your needs.