My application is Reservation System, I want to auto update a values, when entering a form.Exact my pblm is 

I have a field company Name, Occupancy Type and Rate.So i entering Companyname,ocuupancy type when automatically enter a Rate

 

       Company Name              Occupancy_Type                   Rate

       

             aaa                                 Single                             3000

I want to edit that field also.Please help me immediately,