Msqyl database

I was wondering something.. I just moved to a new host with my domain.. did upload my site backup of my previous host..but now i have problems with the msqyl database.. i did backup that one aswell but i cant upload it it seems.. now i wonder how important is dat database concerning old posts and comments etc? can i just make a new one without destroying anything or do i have to upload the old one to make it all work good?
I also gonna upgrade my wordpress but i first want my old one to work