Reminds me of the sqldf project for R [0] which allowed you to work with R data frames and SQL databases with SQL queries.<p>[0] <a href="https://cran.r-project.org/web/packages/sqldf/index.html" rel="nofollow">https://cran.r-project.org/web/packages/sqldf/index.html</a>
This looks very interesting. Have you looked at Substrait.io [1] at all?. The aim of Substrait is similar to what you describe, i.e. to create a universal relational algebra representation that can be executed directly by backend systems without having to go through SQL.<p>[1]: <a href="https://substrait.io/" rel="nofollow">https://substrait.io/</a>