is this feature available while creating sharepoint workflow for a list?

I have a sharepoint list that has a number column call xyz i am creating a sharepoint designer workflow for that list 开发者_如何学JAVAin which i want to use update this list item action

if we chose actions as update this list item then chose the list as current item then chose set this field -> xyz to this value -> { how can i select here current value of xyz - 1 } i.e a variable formula

Do it in two steps. First, declare a workflow variable (I'll call it "sample" here). Then, add a workflow step "do calculation" and set sample to xyz-1. The text line Designer shows you will look like Calculate <workflow name>:xyz minus 1 (Output to variable: sample afterwards.

Then, set the xyz value to current value of sample.