Code inside SQL Cursor will only execute first FETCH - sql

Question

I have a SQL Cursor which I'm having issues with. When I remove the IF #debug = 1 statement from inside the cursor, only the first record from the FETCH will get updated but if I leave the IF #debug = 1 all the required records are updated. Any idea as to why this is happening, I know most likely something is wrong with my Cursor? Code is below:
DECLARE Verify_Shipment_Cur CURSOR LOCAL FAST_FORWARD READ_ONLY FOR
SELECT DISTINCT lpd_shipment_id, lpd_po_number, lpd_customer_id, lpd_sku, lpd_lottable01, lpd_lottable02, lpd_lottable03, lpd_putaway_zone, lpd_pdt
FROM PO_DETAIL01(NOLOCK)
WHERE lpd_shipment_id = #i_SHIPMENT_ID
AND lpd_po_number = #i_POKEY
AND lpd_customer_id = #i_CUSTOMER_ID
AND lpd_status = #AvailableStatus
OPEN Verify_Shipment_Cur
WHILE #ShipmentSKUCount >= #ShipmentSKUCountCur
BEGIN
FETCH NEXT FROM Verify_Shipment_Cur INTO #ShipmentID, #POKey, #CustomerID, #SKU, #Lottable01, #Lottable02, #Lottable03, #PutawayZone, #PDT
IF EXISTS(SELECT 1 FROM PO_DETAIL(NOLOCK) WHERE pd_asn_number = #i_SHIPMENT_ID AND pd_po_number = #i_POKEY
AND pd_sku = #SKU AND pd_type = #ShmtType AND pd_ordered_qty <> pd_received_qty)
BEGIN
UPDATE PO_DETAIL
SET pd_adjusted_qty = pd_ordered_qty - pd_received_qty
WHERE pd_asn_number = #i_SHIPMENT_ID
AND pd_po_number = #i_POKEY
AND pd_sku = #SKU
AND pd_type = #ShmtType
END
UPDATE PO_DETAIL
SET pd_lottable01 = #Lottable01
, pd_lottable02 = #Lottable02
, pd_lottable03 = #Lottable03
, pd_lottable04 = ''
, pd_lottable05 = #Date
, pd_putaway_zone = #PutawayZone
, pd_pdt = #PDT
, pd_status = #VerifiedStatus
WHERE pd_asn_number = #i_SHIPMENT_ID
AND pd_po_number = #i_POKEY
AND pd_sku = #SKU
AND pd_type = #ShmtType
UPDATE PO_DETAIL01
SET lpd_status = #VerifiedStatus
WHERE lpd_shipment_id = #i_SHIPMENT_ID
AND lpd_po_number = #i_POKEY
AND lpd_customer_id = #i_CUSTOMER_ID
AND lpd_status = #AvailableStatus
IF #debug = 1
BEGIN
SELECT #ShipmentSKUCount AS SKUCOUNT
, #ShipmentSKUCountCur AS SKUCOUNTCUR
, #SKU AS SKU
, #ShipmentID AS SHIPMENT
, #POKey AS POKEY
END
SET #ShipmentSKUCountCur = #ShipmentSKUCountCur + 1
END
CLOSE Verify_Shipment_Cur
DEALLOCATE Verify_Shipment_Cur

Answer 1

It looked ok to me but i obviously dont have your data to assist. Can I recommend putting a few print statements in various parts of your cursor. That way you can see how the code is actually flowing. It doesnt help but thats what I would do.

Answer 2

Please, can you try to define explicilty both variables: set #ShipmentSKUCount=[initial value],set #ShipmentSKUCountCur=[initial or constant value] and see what will happen?
Also, I found there is no checking for a ##FETCH_STATUS. It may also result into reading same row twice or more.
Please, give a feedback.