将下拉选项更改为按钮

I am trying to change the drop down option to button. But i was unable to do it. The code i have was done by a professional but i am quite new.The drop down option is taking the values from a databaseand displaying it. The drop works as if any user selects the currency the values of the items also changes according to it.

<div id='curr_picker''>
          <strong >Currency:</strong>
<?php
$curr_query = "SELECT * FROM `currency_sett` WHERE `curr_id` >= '1'";

              $curr_result = $mysqli->query($curr_query) or die ($mysqli- >error);
              if($curr_result->num_rows > 0){
                while($curr_row = $curr_result->fetch_assoc()){
                  $curr_id = $curr_row[curr_id];
                  $curr_code = $curr_row[curr_code];
                  $lower_curr_code = strtolower($curr_code);
                  $prefix = $curr_row[curr_pref];
                  $suffix = $curr_row[curr_suff];
                  $format = $curr_row[curr_form];
                  $base_rate = $curr_row[base_rate];

                  $calc_monthly_price =  $base_monthly_price * $base_rate;
                  $calc_quarterly_price =  $base_quarterly_price * $base_rate;
                  $calc_semi_ann_price =  $base_semi_ann_price * $base_rate;
                  $calc_ann_price =  $base_ann_price * $base_rate;

                  if($curr_id == $page_load_currency){
                    $selctd_opt_attr = "selected='selected'";
                  }
                  else{
                    $selctd_opt_attr = NULL;
                  }

                  if(!in_array($curr_code, $curr_shown_array)){
                    $disp_curr_opts .= "<option value='$lower_curr_code' $selctd_opt_attr>$curr_code </option>";
                    $form_inp_hidden_var .= "<input type='hidden' id='curr2id_{$lower_curr_code}' name='curr2id_{$lower_curr_code}' value='$curr_id'>";
                    $curr_shown_array[] = $curr_code;
                  }
          echo("
          <div class='selectouter'><select name='pick_currency' id='pick_currency' '>
            $disp_curr_opts
          </select></div>
          <div style='display:none;'>
          <form>
          $form_inp_hidden_var
          </form>
          </div>
          ");
          ?>  

          </div>

i was able to change the drop down to button

$disp_curr_opts .= "<input type='button' id='button_{$lower_curr_code}' value='$lower_curr_code' />";

But now i am stuck as i dont know how i will implement the onclick and which part of the code would go under it. So can anyone help me how should i do it? If some also helps me understanding how the code is working incase of the dropdown mentioned it would do a great help.