How to find differences week over week?

[scweiss1]

Hi! 

Apologies if this has been asked before - I’m having a hard time figuring out even what question to ask.

I’m very new to Looker and trying to leverage the product to eliminate a lot of manual Excel work.

The problem: Create a Look where analysts would be able to see which names appeared on a list that don’t on another.

Let me be more concrete with an example.

Imagine a sign up sheet for a weekly event. It is simple and tracks the date of the event and the name of the attendee. Each week, we just add more lines the sheet.

| Date | Name | 

| 2022-01-01 | John | 

| 2022-01-01 | Jennie | 

| 2022-01-01 | James | 

| 2022-01-08 | John | 

| 2022-01-08 | Jennie |

| 2022-01-08 | Jim |  

In our example, James didn’t show up for the event on the 8th, while Jim, who wasn’t present on the 1st, did. 

I’d like a report (or two) that can compare two target time periods to say Person A is new and a separate report to say Person B is missing.

Building on the example above, if I compare January 8 to January 1, I’d have one row in each report.

• For the adds report it would show Jim.

• For the losses report it would show James.

Is this possible?

The closest thing I found was this question, which was I don’t _think_ was quite what I needed.

https://community.looker.com/explores-36/any-known-equivalent-to-sql-not-in-6061

Thanks!