I won’t put this on the main site, as it is primarily opinion based.
I have self-taught MySql skills, and a PostGis book on the way from Amazon :-)
I am an embedded programmer, with *cough* decades experience. I have self-taught PHP & MySQL on & off for about 20 years and Angular 1.x on & off for about 7.
My SQL skills are basic CRUD. I know how to 3rd order normalize, but nothing about optimization or more advanced stuff.
I am about to take a few GIS courses from Coursera. Should I take a detailed SQL course first? I feel confident with CRUD.