Libraries written in SQL. I'm sure one can search for let's say a snippet that will create a date dimension table for a data warehouse and copy it but it's pretty clunky compared to even Python modules.

I'm criticizing SQL as a language which is lacking in composability (as opposed to criticizing relational algebra or relational data model).

Libraries for working with SQL (full-fledged ORMs or simpler query builders) are themselves written in a different language so they don't necessarily prove anything about SQL itself, though one could argue that if people want to use them then they might not be satisfied with raw SQL.