I am in SP 2016. I have a customer and orders lists. Using my workflow, I am retrieving customer id from the customer list. I want to use the same id to grab information from the orders list. But before doing that want to check if that entry is already there in the Orders list. 

I am thinking of creating a switch or if then statement. If record is there, update it. If not, create it. How do I check if the record is already there. How do I check for blank values?

Your help is appreciated.