当从高到低点击时，它在数据库中没有显示产品

Want to sort price by cat_id when clicked on product from dropdown category product will open in results.php page,when clicked on high to low it is showing no product in database

 'template_header.php
  <?php
 $category_sql = ("SELECT category.cat_id,category.cat_name,  
 subcategory.sub_id, subcategory.sub_name  
 FROM category ,subcategory 

 WHERE  category.cat_id = subcategory.cat_id 

 AND category.cat_name='Mobiles'");
 $category_query = mysql_query($category_sql) or die (mysql_error());
 $rscategory= mysql_fetch_assoc($category_query);
 ?>

 <div id="div1">
  <li class="menu_left"><a href="index.php" class="drop big  style5">Electronics</a>
    <!-- Begin 3 columns Item -->
    <div class="dropdown_6columns align_left">
      <!-- Begin 3 columns container -->

      <div class="col_1">
      <p><strong><a href="results.php?category=<?php echo     
                     $rscategory['cat_id'];?>"><?php echo 

          $rscategory['cat_name']; ?></a></strong>
       <?php do {
           ?>   
      <a href="results.php?subcategory=<?php echo $rscategory['sub_id'];?>"> 
       <?php echo $rscategory['sub_name']; ?></a>
           <?php
           }while($rscategory = mysql_fetch_assoc($category_query));
           ?>
        </p>