Creating Custom Query

Try following codes:

    $country_search_array = array();
    while($row = mysql_fetch_array($regionresult)){
        $country_search_array[] = $row['country']; // Your country field name
    }
    $country_search = "'".implode("',", $country_search_array)."'";

$args = array(
        'posts_per_page' => -1,
        'meta_query' => array(
            array(
                'key' => 'Country',
                'value' => $country_search,
                'compare' => 'IN'
            )
        )
    );
    $query = new WP_Query( $args );