Comment by snuxoll

I mean, I get it, but the big problem is, again, the different phases of execution. The projections you perform with a select can be absolutely arbitrary and do crazy ass things (like do more subqueries that return scalar values, and query planners are notoriously bad at pushing these down), which is why I was trying to say SELECT before WHERE (project before filtering) may be linguistically intuitive, but full of foot guns.

Something like a ‘let’ binding after the FROM/JOIN list would make sense, though - from the query planners perspective it’s nothing more than a token substitution and everything would compile the same.