Yeah but the functions and style used in these answers vary across implementations (date_trunc, etc.) I highly recommend the SQL Cookbook for newer SQL dev as

Yeah but the functions and style used in these answers vary across implementations (date_trunc, etc.) I highly recommend the SQL Cookbook for newer SQL dev as a quick reference comparison to see how often this is the case for even trivial problems in any RDBMS. Also, for your language I wouldn't expect all mid tier SQL devs to be able to write a recursive CTE from memory (though its useful, you can just look it up again), but something like breaking apart a query plan on your platform of choice is way more important as that muscle allows you to tell if your CTE was crap or not.