Everyone should know how to query a DB, but network programming seems to me like a niche within a niche (systems programming). I have done tutorials on writing TCP or doing a server in C but never came anywhere close to writing that stuff in practice.
I was thinking a basic SELECT X FROM Y WHERE Z Sql query that can be learned in a day by someone familiar with programming. I don’t know enough to know what qualifies as advanced.
That's fair enough if your job is in front end or whatever and you just need to use a table or view that someone else built for you.
I comment I read somewhere was that SQL goes from basic to advanced with nothing in between. It's a slippery slope of course: you start writing your own query and then you figure a more sophisticated query would be helpful and pretty soon you're having to care about optimisation and indexes.