Consult id from database to variable

I am creating a project in which I applied an autocomplete to a textbox that loads a list from the database. The database has a column "zones_id" and another "destinationall", I intend to obtain the id of the destination selected by the autocomplete, and store it in a variable and then make a comparison with it, but I'm not sure how to execute the query of the id at the same time to store it. I appreciate your attention!

PHP:

<?php
include("conexion.php");
$sql = "select id_zona, destinostodos from destinos order by destinostodos";
$res = mysql_query($sql);

$arreglo_php = array();
if (mysql_num_rows($res)==0)
array_push($arreglo_php, "no hay datos");
else {
    while ($palabras = mysql_fetch_array($res)) {
        array_push($arreglo_php, $palabras["destinostodos"]);
    }
}
?>

Script:

<script type="text/javascript">
$(function() {
    var vec_pal = new Array();
    <?php
    for($p = 0;$p < count($arreglo_php); $p++) { ?>
        vec_pal.push('<?php echo $arreglo_php[$p]; ?>');
        <?php } ?>
        $("#destination").autocomplete({
            source: vec_pal
        });
});

HTML

<!-- Form: Destino -->
  <div id="destino" class="reserva">
    <div class="form-group">                     
        <input type="text" placeholder="Destino: Hotel, Villa o Ciudad" class="form-control" name="destination" id="destination">
    </div>                
  </div>