Basic SQL sure, but the moment you start getting into complex operations, upserts, extensions, functions, custom aggregate operators, arrays, HStores, etc it gets complicated. At least for me.
I would not be able to do this super quickly: https://stackoverflow.com/a/42939280
The finer points probably require a bit more than that.
If you're already technically proficient in general programming (or Excel), you're likely to pick up SQL quickly.
There is immense, unwarranted filtering of people from jobs for relatively minor things.
To all the naysayers and downvoters: There's a difference between knowing SQL and being an SQL ninja or a master of database architecture. Those are three different things. The former, and what my original comment concerned, was just learning the language itself.
I concede that learning to be able to craft complicated, performant queries and design complex databases with any desired property you might dream of is not quick or easy, but I still maintain that learning the language itself (sans extensions) is.