I have a SQL Server table with a list of files (path + filename), and a folder with multiple layers and files in each layer. I'm looking for a way to reconcile the two without having to process the list twice. Currently, I'm doing this:

For Each f as FileInfo In FileListFromDatabase
   If f.Exists is False, mark it as deleted in the database
Next

For Each f as FileInfo In RecursiveListOFFilesOnDisk
   If Not FileExistsInDatabase, then add it
Next

Is there a better way to do this? I'd like to avoid converting all the matching files (of which most will be) to FileInfo objects twice. Since I'm a T-SQL developer first, I'm picturing something like an OUTER JOIN of the two lists where they don't match. Something LINQ-ish?