First of all, a spec on dbf files would help, you'll need to parse it apart using fopen/fread/fseek/etc function, and insert the data into the database accordingly, creating sql tables on the fly if need be, or cleaning out the table every time this is run, etc.
There's no easy way to do that, that I'm aware of, a custom solution sounds to be in order.
If you don't think you're up to this type of work, then you're in luck, my company does, just follow the link in my sig.