function getCategories($id = null) {
      $categoried = array();

       $query = mysql_query("SELECT id,name FROM `categories`");

      while ($row = mysql_fetch_assoc($query) ) {
              $categories [] = $row;
     }

...
             <select name="category">
                  <?php
                     foreach(getCategories() as $category){
                  ?>
                  <option value=" <?php echo $category['id'];?> " > <?php echo $category['name'];?> </option>
                  <?php
    }
    ?>