divide two fields

Hello everyone,

I’d like to divide two fields one is a custom field and the other is IFS stander. 

I created the following query

SELECT (shm.Qty_Required) / (cfv.CF$_STANGGENGEWICHT) FROM Shop_Material_Alloc shm, Inventory_Part_Cfv cfv

First, I get the wrong result, what is the problem in this query?

Secondly, the field “Qty_Required” from view “Shop_Material_Alloc” includes wights in kg and pc’s. 

Now I need to divide only the attribute “qty_required” on the those in kg only and not that include pc’s.

can anyone help?

Thanx in advance