Need help with halo odst!

Ive never played ODST but ive beat Halo 3 on legendary and im rank 203 online. But i sold the game over 10 months ago and i now want to get ODST but do i need halo 3 to play ODST? and also if i dont have halo 3 and i buy ODST, will my stats and ranking (203) transfer over to ODST? thanks!

You need to stop posting this when everyone has answered your question already.

I think you posted about this topic enough times already.