SQL Joins Visualization
Interactive tool for sql joins visualization
Every pure database developer could confirm that SQL language can be compared if not to the mother tongue but at least to any other foreign language you know. I.e. it's not a programming language. It's a more verbal, human-like tongue.
Jokes aside, this is just an expression of respect to the simple but very powerful language that allows you to "speak" to the different databases.
Being so widely used it's assumed by default today that every developer who ever wrote any piece of backend code must know SQL language.