Do you SQL? Salesforce Marketing Cloud

If you asked me “how do you find segmentation in Salesforce Marketing Cloud?” a few years ago, at the beginning of my experience with the tool, I would have rolled my eyes.
Yes, I said it, I would have rolled my eyes.

Why? Well, I am not a developer, I am not a coder and let’s say the user interface for segmentation in SFMC is quite limited compared to other technologies I have worked with in the past.
Sure, we can filter data extensions, split them, clone them and potentially use data relationship to connect multiple tables and cross filter them.
However, that day will come. The day in which none of the above will suffice and you will have to face an empty SQL activity and get the blank page syndrome.

I was lucky enough to find myself in this situation on my first assignment.
The architect I was working with was great and had a lot of knowledge, but also wanted me to fail and learn from my mistakes. He sent me to figure out how to create a segment that required to join 3 tables.
I got some directions from some of the devs in the offices, heard them talking about joins, left, right, inner, outer and I could even picture what they were referring to.
I started googling.
Brace yourself. The image I am about to share has been my guiding angel from the moment I found it and still is.