> always creating an intermediary result-set

You want the DB to first run SELECT * FROM <table>, and then start operating on that?

Obviously not, and bringing this up as if it's a gotcha just shows you aren't keeping up with the conversation. Try less to correct people and more to understand people.

It's about how humans think about it, not about how the computer executes it.

How else do you read what they wrote?

I read it as describing their preferred mental model for declaring a result set, which is different from describing their preferred behavior to produce it. This seems clear to me in wording and context; it’s also broadly consistent with how SQL is understood, and how it is generally implemented.

Presumably, the intermediate result sets would necessary be materialized, only logical.

How would this approach support SQL constructs such as the HAVING[0] clause? Or is that what you meant by:

  WHERE sum(d) > 100 -- the above with having sum(d) > 100

0 - https://www.w3schools.com/sql/sql_having.asp

My other big dream would be allowing multiple WHERE clauses that would be semantically ANDed together because that's what would happen if you filtered a result set twice.

Yes! I've always been annoyed by this.

Yes, by whatever clauses I also meant repeating ones.

SQL has a conceptual issue with repeating group by clauses, so maybe not that one (or maybe we should fix the conceptual issues). But any other, including the limiting and offset ones.