(Around 2010 I was frustrated with the state of OWL/RDF/SPARQL and all that and was curious about Datalog and found it was truly obscure and hard to find good reading about, interest in Datalog has exploded since then.)
Note SQL has subqueries and in some sense is "composable", there are even some advanced features like
it is ugly as hell and has problems with consistently using unique names (like the "hygenic macro" problem) but you can write crazy-complicated queries in SQL.