Fetching values from database for select box

You can used below code to get results from the database in wordpress.

global $wpdb, $posts;
$prefix = $wpdb->prefix;
$query = $wpdb->get_results("SELECT * FROM {$prefix}states");
if($query){
    echo '<select><option value="select">Select</option>';
    foreach ($query as $value) {
      echo '<option value="'.$value->ID.'">'.$value->ID.'</option>';
    }
    echo "</select>";
}