I'm looking for the name of a song from either "The Nutcracker" or "Swan Lake?"?

It's a famous song, but I'm not sure what the name is. I'm pretty sure it's either from The Nutcracker or from Swan Lake. It's playable by the piano since I've heard sheet music for it and the song is played by the piano, not an orchestra. I've often heard it in hotel ballrooms, lobbies, or restaurants. It'd be very helpful, thank you very much.