I think it's important to reinforce that SQL isn't an COBOL like attempt at building a querying language out of natural expressions (which you could see if you squint really hard). Instead SQL is a refinement of various querying languages (hence being the standard one) that co-evolved with relational algebra. If you have a chance to learn more within an academic environment courses on relational algebra and the abstract theory of set operations can be invaluable to building a basis for more naturally understanding the intent and tools available in SQL.