There is some List <> that is in memory.
Can I somehow implicitly connect to the table from the database (ORM is not there)?
I have an idea, to create a # table and in it to make an INSERT from a sheet, and then a request to perform a connection, but can there be any implicit approach that will do it for me?
You can still generate a request with IN and send it to the server, but this is not universal, since IN has limitations on the number of values, and IN in performance is slower than JOIN.
IN. So test, and on your data. Performance issues without testing - guessing the coffee grounds. - VladD