Update field in one data type by adding item's quantity in another data type in the same workflow

[brandesign11]

Hi,
I have a data type “Proizvod” where I add/remove products from database. I created new data type “Unikatniproizvod” where I would like to store (increase/decrease) only unique products with quantity in entire stock. I have a workflow where I add new item to “Proizvod”, and here I would like to add step where I would like to check if item with the same name already exists in “Unikatniproizvod”, if no, to add it, if yes to increase field quantity.
Thanks for your help!

[achen2222]

in your only when at the bottom

do a search for a unikaprozvoid with name = whatever the name is :count =0