Two classical pieces

OK, this is going to be hard to describe. I'm looking for two classical pieces of music that you will almost certainly have heard, but I don't know who wrote them (perhaps Tchaikovsky?). So I guess I have to describe them by sound.

The first goes: DA, da DA, da da da da da DA! DA, da DA, da da da da da DA...
(I think it was on a McDonald's advert around 1999 or 2000, if that's any remote bit of help)

The second is much bigger: Dadada dadadada da dadada...
(It sounds more French, a sort of tune like the can-can, but again hard to tell)

If anyone can help, I would be very grateful, as Shazam is useless when it comes to classical music!

Well I managed to rather quickly find the second piece, called "Trepak (Russian Dance)", which was indeed by Tchaikovsky. I'll see if I can save any further trouble by finding the other one.

Found the other piece at last - "Eine Kleine Nachtmusik" by Mozart! Thanks anyway.