https://prql-lang.org/ might be an answer for this. As a cross-database pipeline...

drittich 11 months ago | parent | context | favorite | on: Vanna.ai: Chat with your SQL database

https://prql-lang.org/ might be an answer for this. As a cross-database pipelined language, it would allow RAG to be intermixed with the query, and the syntax may(?) be more reliable to generate