I’ve read most of Codd’s book on the subject and have written SQL on and off since the mid 90’s and I still need to look up the differences between the various joins anytime I use them.
A junior in SQL would need AI to write things they're not sure about, the same way stackoverflow has helped us for many many years before AI. A senior in sql, and in fact any languages, would use AI to be accelerated (I know I do).