How can I get over my fear of dentists?

I have always been afraid of the dentist, and I have had cavities when I was younger, but now the dentist absolutely terrifies me! It makes me want to be sick just imagining the dentist looking at my teeth, because I'm always scared that he will find a cavity. I know that cavities don't hurt because they numb it but I'm still scared of the dentist drilling my teeth. Could somebody please help me?