I finally finished the challenge, but there was just one thing I feel I was missing. I knew a little about SQL, but I didn't know about the UNION ALL command. After reading about it, I used it properly and I got the emails. Problem was, I sort of guess the number of columns. It worked out, but I don't feel that was the point.
Reading the threads I discovered there was a way of finding out the number of columns with order by (hope this isn't a spoiler, it was posted before). But never understood how to do it, I googled it and everything but can't find the solution. I might be googling for the wrong keywords, since I can't find anything on my native language.
If maybe someone could explain me, or maybe point me to the correct article/information I would really really appreciate it. I'm not asking for the line of code that would make it work, but the explanation of how and why it works that way. If somebody feels like helping out an annoying noob, I'll be waiting. Thanks!