I'm new so this may be a dumbass question but when you say using a database in corespondence chess you're referring to looking up old games in Chessbase right? Not plugging the moves into Houdini or Komodo and asking the comp for the next move....
Yes. ChessBase, Chess.com Explorer, Chess Informant, New in Chess, old dog-eared books, SCID vs PC, opening monographs, Nunn's Chess Openings, ...

you cant control it