Check for Duplicates from Existing Spreadsheet

Hey! I’m looking for some ideas on how to accomplish a goal. I don’t need any specific examples, just a push in the right direction.

Let’s say that I want to build a spreadsheet of people that have attended a meeting on a given day, but only if they have not attended a meeting before. I have created workflow that scrapes the names from an attendance list and creates a spreadsheet of names that have ever attended the meeting. Let’s call it the Master List. I’ve also created a workflow that creates a spreadsheet of names that have attended a specific meeting. Let’s call it the Daily List.

However, I want the Daily List to only include people that are not on the Master List. So, basically the new attendees. I know how to use the “If” activity, but what activity would I use inside the “If” activity to see if the person is on the Master list? Is that the “Collection” activities?

Thanks for your help!

Do you want to remove the list while creating the daily spread sheet.

Or you want to compare two spread sheets after they have been created? (Using data tables would be easy)

I would like to check the Master List while creating the Daily List and only add names if they are not on the Master List. I prefer not to delete names from the Daily List after it is already created.