title: On change form_dropdown codeigniter
body: <p>I am working on form_dropdown() in codeigniter.</p>
  
  <p>I have table countrystate(id, countryname, statename)</p>
  
  <p>I populated countryname &amp; filled on form_dropdown('fd_country').</p>
  
  <p>Now I want to display statename based on selected countryname. Please help.</p>