Support for DuckDB

[NatElkins]

Support for DuckDB

[Thorium]

The first thing SQLProvider will need is a way to query information schema: table names, column names and column types. And some kind of db-type <-> .Net type map.

This doesn't use EF (it was way too big, complex and slow, and it compiled the whole DB, not only part you need), instead this translates LINQ tree to it's own simple SQL AST (type SqlExpr) common to all providers and a provider just translates that to an SQL clause.

Typically I've seen people to create new db providers just by copying an existing one and then rewriting the function content. Here are some design info, but a lot of that is not even needed to know for writing a new provider: https://fsprojects.github.io/SQLProvider/core/techdetails.html