LINQ stands for Language-Integrated Query and is incredibly successful at its purpose of providing powerful querying functionality and extensions baked into the C#/.NET language space itself.

This querying framework is what powers translations and compilation into SQL and several other languages (depending on the datastore provider used).

EntityFramework is one of the most advanced ORMs out there and is supremely productive because of LINQ.

LINQ is stunningly successful, LINQ Query syntax (what you probably are referring to) with LINQ to SQL less so.

And yes, as usual, we have the amazing confusion of Microsoft Naming.

But query syntax is essentially just a way to use an ORM that looks closer to SQL but is strongly typed.

LINQ creates an AST in the .NET land, however, before passing it to an actual SQL database, it serializes the expression tree to SQL.

So no, it does not talk AST to the database.

No, it never tried that.