Remove rows where one row offsets the next using accounting rules - sql

Question

I have a view of materials data which contains what was purchased and reversals of some of the purchases. I need a query that removes records that have reversals of purchase transactions. NOTE: The view does not have a primary key.
In the example I need to remove the first two rows as the second row offsets the first row because it reverses the purchase, but I need to keep the third row. Any ideas?
Here is the SQL for the view:
SELECT LEFT(mi.Plnt, 3) AS SBUID ,
oth.EQUIP AS PROJECTID ,
ms.Req_No AS GI ,
ms.Req_Item AS GI_LINE ,
CONVERT(VARCHAR(11), [Doc_Date], 100) + ' 12:00 AM' AS DOC_DATE ,
mi.[SLoc] AS SLOC ,
[Material] AS MATERIAL ,
mi.[Description] AS MATERIAL_DESCRIPTION ,
[Qty] AS QUANTITY ,
mi.[UoM] AS UOM ,
CASE WHEN mi.Mvt IN ( '101', '103', '105', '123', '261' ) THEN
mi.Amount
ELSE mi.Amount * -1
END AS Cost ,
mi.Amount AS EXT_ORG_COST ,
mi.PO AS [PO] ,
mi.Batch ,
mi.Vendor AS VENDOR ,
mi.VendorName AS VENDOR_NAME ,
at.AC_Group AS AC_TYPE ,
[Mvt] AS MVT
FROM [dbo].[MatIssued] mi
INNER JOIN dbo.OrderTableHistory oth ON oth.SUB_ORDER = mi.SubOrder
INNER JOIN dbo.Aircraft_Information2 ai ON ai.Equip = oth.EQUIP
INNER JOIN dbo.RFC_AcftTypeList at ON at.ID = ai.AC_TypeID
LEFT OUTER JOIN dbo.MatStatus ms ON ms.MPN = mi.Material
AND ms.SubOrder = mi.SubOrder
WHERE mi.Plnt IN ( '9131', '9132' )
AND mi.Mvt IN ( '101', '102', '103', '104', '105', '106', '122', '123' ,
'261' ,'262' )
AND mi.Doc_Date >= DATEADD(YEAR, -1, GETDATE())
ORDER BY mi.PO ,
mi.Batch ,
PROJECTID ,
mi.Mvt;

Answer 1

Some assumptions, based on your screenshot:
Reversals have same DOC_DATE as purchases
Reversals have same Batch as purchases
If the above assumptions are correct, try something like this:
DELETE FROM t
FROM MyTable t
WHERE EXISTS (
SELECT 1
FROM MyTable t2
WHERE
-- Join to outer table
t2.SLOC = t.SLOC
AND t2.MATERIAL = t.MATERIAL
AND t2.QUANTITY = t.QUANTITY
AND t2.PO = t.PO
AND t2.Batch = t.Batch
AND t2.VENDOR = t.VENDOR
GROUP BY SLOC, MATERIAL, QUANTITY, PO, Batch, VENDOR
HAVING COUNT(*) = 2 -- There are 2 matching rows
AND -MIN(QUANTITY) = MAX(QUANTITY) -- Minimum quantity negates Maximum quantity
AND MIN(COST) + MAX(COST) = 0 -- Costs cancel each other out
AND MIN(CASE WHEN Cost > 0 THEN DOC_DATE END) <= MIN(CASE WHEN Cost < 0 THEN DOC_DATE END) -- Purchase DOC_DATE less than or equal to reversal DOC_DATE
AND MIN(MVT) = MAX(MVT) + 1 -- Correlate purchase and reversal movement
AND (t.DOC_DATE = MIN(DOC_DATE) OR t.DOC_DATE = MAX(DOC_DATE)) -- Join to outer table
)