Which courses have problem in commands.

Question

I heard SQL course have many problems (like there isn't SHOW command), i want to know which courses are like SQL in this problem and i shouldn't learn them.

This is a user comment in sql course:
I'm a professional Microsoft stack developer. C#, SQL, etc. I'm here because i want to see what this course teaches for a friend who found SoloLearn who i'm teaching to program. And i have to say, this is sad that SoloLearn teaches this as SQL when it is not! SoloLearn, please teach people that there is a SQL standard. if u didn't know this, then please learn about it yourself. and if something like SHOW DATABASES doesn't work in one free implementation of SQL, tell the reader. this doesn't work in Microsoft SQL. anyways folks, now you know that there is a standardized SQL and SoloLearn hasn't informed you of this (yet?) in this course. of course i don't know what's after this page in this course. but still, SoloLearn is a haphazard tutorial, not the best, but it's not bad either. i like SoloLearn so far, overall. bu