[zasdffaa]

@wruza, @wenc: These are both very good answers, and you are of course both right. Check the symbol table, anything you can't find should be defined in the same context (in the select list, as a new expr). In which case, match each symbol use (eg. x in x * x as y) to the definition (eg. 1 as x) to establish a set of dependencies, then do a partial order sort, then spit out the results.

I can do that I just don't fancy it, and more to the point nobody is giving me an example of where it would be particularly helpful. So if anyone can, I'm interested.

(also, consider human factors; although an acyclic definition could be extracted from an unordered expression set, a consistent left to right (in the western world anyway, matching textual layout) with dependencies being introduced on the right and depending only on what came before on the left might actually be better for us meatsacks)

[wruza]

My examples are from boring enterprise, not from what we love to create at home. I’ve read and patched literally meters long queries in analytics, which could be reduced dramatically by being self-referential and by other approaches discussed itt. Of course these could be refactored into something “create view/temp/cte”, but that requires a full control of ddl, special access rights and code ownership. Most space was used by similar case-when-then constructs and permutations of values these produced. The original code was on official support, so we couldn’t just rewrite it, because migrating to the next update would cost a week instead of an hour.

I could reach to and post a lenghty example, but it’s nothing but boring reshuffles really, spiced with 3-level joins of “modelling db in db to allow user columns”.

I agree on the LTR idea, because reading a symbol not yet defined may lead to confusion.