title: recursive function to get all the child categories
body: <p>Here is what I'm trying to do:
  - i need a function that when passed as an argument an ID (for a category of things) will provide all the subcategories and the sub-sub categories and sub-sub-sub..etc. 
  - i was thinking to use a recursive function since i don't know the number of subcategories their sub-subcategories and so on
  so here is what i've tried to do so far</p>
  
  <pre><code>function categoryChild($id) {
  
      $s = "SELECT * FROM PLD_CATEGORY WHERE PARENT_ID = $id";
      $r = mysql_query($s);
  
      if(mysql_num_rows($r) &gt; 0) {
  
          while($row = mysql_fetch_array($r))
              echo $row['ID'].",".categoryChild($row['ID']);
      }
      else {
          $row = mysql_fetch_array($r);
          return $row['ID'];
      }
  }
  </code></pre>
  
  <p>If i use return instead of echo, i won't get the same result. I need some help in order to fix this or rewrite it from scratch</p>