# Designer workflow to do a calculation from info found on two lists

• ### Question

• I've racked my brain trying to figure this out but no luck.

List A - This where i keep my customers order info. PO#, Qty, and Item are the important ones for this question

List B - This is where i keep info about the PO's i have open for the customer. The columns i have on this is PO#, Open for qty, Qty Used, Qty left (this one's calculated to subtract used from open

My goal is to have it set up so when i enter info about an order in List A, i would like it to update thE qty used column in list B (in a row that matches the PO and Item number).

Is there a way to do this. My most recent thought was if i added a column to list a that showed just the qty's for the PO/Item i wanted and zero'd anything that didn't match that criteria and turned on the totals row to add all the qty's in that column then i could use designer to say "take totals from list A in column X and insert in List B in column Y"  But so far i haven't been able to figure out how to do that.

If anybody can help me figure this out or offer suggestions i would be very gratefull

• Edited by Thursday, May 24, 2012 9:06 PM to make more sense
Thursday, May 24, 2012 9:04 PM

• Hi mandy996,

From your description, if I’m not misunderstanding, you want to calculate the total Qty Used value in listB based on the Qty value in listA, if so, you may try to create a column in listA to store the oldQty value before update the item, then use a calculation formula:
QtyUsed = QtyUsed + listA:Qty(listA item Qty after update)-oldQty(listA item Qty before update)