public void cb(JComboBox cb,String a,String id){
        con.ConsultarSQL("SELECT id,"+a+" FROM "+a,true);
       try {
           con.rs.first();
           cb.addItem("Selecionar....");
           int index = 0;
           do{
               index++;
               cb.addItem(new InseriIdCombobox(con.rs.getString("id"), con.rs.getString(a)));
               if(con.rs.getString("id").equals(id)){
                   cb.setSelectedItem(cb.getItemAt(index));
               }
           }while(con.rs.next());
           
           int as = Integer.parseInt(id);
           cb.setSelectedItem(as);
           
       } catch (SQLException ex) {
           System.out.println("erro na tb");
       }
    }