Unexplanations: sql is syntactic sugar for relational algebra
This idea is particularly sticky because it was more or less true 50 years ago, and it's a passable mental model to use when learning sql. But it's an inadequate mental model for building new sql frontends, designing new query languages, or writing tools likes ORMs that abstract over sql.
https://www.scattered-thoughts.net/writing/unexplanations-sql-is-syntactic-sugar-for-relational-algebra/