That can be tough if you feel like everyone else has a date but not you. I guess it varies from school to school. At my frriend's school, everyone in her friendship group has a boyfriend/girlfriend, so they're all going together as couples. Just because she doesn't have a date, doesn't mean she will have tto stand by herself all night; her friends will still talk to her and its likely to be onoy a few slow songs that they want to be alone for, then they'll hang out as a group of friends.
At my school, virtually no-one is dating anyone, so everyone is going in groups of friends. Are you sure that everyone is going in couples? If they're not, then you don't neeed to worry about being the only one with a date :)