How to discount a lot of products at the same time?

Q: Is there way to discount a lot of products at the same time? 200 of my clients 300 products get a 20% discount, does it have to be done one by one or is it possible to do that in one click?

A: Quickest way would be add all the 200 products to a new category and use the https://jigoshop.com/product/customer-discounts/ plugin to assign a 20% to each product in that category.