Slight incompatibility with DuckDB

[max-sixty]

Currently, querying files in DuckDB doesn't quite work without an alias, because:

from products.csv
filter supplierID == 1

compiles to:

SELECT
  products.csv.*
FROM
  products.csv
WHERE
  supplierID = 1

And actually products.csv.* isn't valid.

We could get around this with just select * when that's all that's needed. This would be valid in every dialect, I think.