A header might be useful, although there’s likely better ways to (not) document what each sql statement does.
But inline documentation? I’d suggest trying to work around that. Here’s an explanation as to why: youtu.be/Bf7vDBBOBUA
If possible, and as much as possible, things should simply make enough sense to be self documenting. With only the high level concepts actually documented. Everything else is at risk to be outdated or worse, confuse