>SQL is much more powerful than most people think, and taking an afternoon to learn everything you can do with it is a great investment.

SQL is indeed powerful but how can anyone learn SQL well in an afternoon?

Maybe I'm mistaken, but I think someone who is already using a relational database through an ORM can learn enough to make powerful queries in an afternoon.

Let's see what we need:

  - SELECT a,b,c FROM table WHERE condition : 1 hour

  - INNER JOIN, LEFT JOIN : 1 hour

  - GROUP BY, HAVING, aggregation functions: 1 hour

  - subqueries, EXISTS : 1 hour

  - recursive queries : 1,5 hours

  - end of the afternoon

You'll probably need to practice a little after that intense afternoon, but I do think that after learning just the five points above, you can become the most knowledgeable person about SQL in your team.

You originally said "everything you can do with it" rather than just the basics though. Those goal posts moved pretty far.

I agree with learning most of your examples in an afternoon, but really knowing SQL takes a hell of a lot longer than that. In fact even the most SQL shy ORM preferring devs I've worked with still know those basics.

Where do you work? That must be a great place! Most devs I know, even talented ones, have never done a recursive query, and a lot of them don't even know it's possible.