Run workflow 1 over 3 lines

Hi all,

I have a list of items with prices in my DB.

I want to build a workflow (backend) that increases the price of the items for only 1 over 3 lines:
line 1, line 4, line 7, line 10.

How can I do it ?

You should search for list shifter plugin and check out the showcase thread and learn how to use it…I suspect it will be able to do what you are looking for.