class Visual < ActiveRecord::Base

 establish_connection :vtest

 self.table_name = 'employee'


 Visual.inheritance_column = 'inheritance_type'

 belongs_to :user

 def emp_matches(x)
   (x.id.to_i == self.id.to_i ? true : false)
 end
end

class UserController < ApplicationController


   def populate_form

     @visual = Visual.find_by_id(params[:emp_id])

     if @emp_matches == 'False'

       respond_to do |format|

         format.json { render json: @user.errors, status: :unprocessable_entity, flash[:error] => "Error No ID found." }
     end

   else

     @visual = Visual.find_by_id(params[:emp_id])

     @emp_first_name = @visual.first_name

     @emp_last_name = @visual.last_name


      render :json => {

         :emp_first_name => @emp_first_name,
         :emp_last_name => @emp_last_name
      }
  end
end

$(document).ready(function(){

   $('#emp_id').change(function() {
         var url = "/user/populate_form?emp_id="+$(this).val();
         $.getJSON(url, function(data) {
           if(!(data.emp_first_name === undefined))
           $('#emp_first_name').val(data.emp_first_name);
           if(!(data.last_name === undefined))
           $('#emp_last_name').val(data.emp_last_name);
         });
       }
     );
   });

Table is called Employee
        ID
        first_name
        last_name

Table is called User


        emp_id
        emp_first_name
        emp_last_name