<?php
/*
This funtion will display posts for each parent categories
*/
function posts_by_cats($num_of_posts) {
    global $wpdb;
 
    // query the cat id
    // remove `parent` = 0 to display all categories
    $sql = "SELECT `term_id` FROM $wpdb->term_taxonomy WHERE `taxonomy`='category' AND `parent` = 0 AND `count` != 0";
    $cats = $wpdb->get_results($sql, ARRAY_A);
 
    //display posts for each cat
    foreach ($cats as $cat) {
      $cat_id = $cat['term_id'];
 
      // query the cat name
      $sql = sprintf("SELECT `name` FROM $wpdb-&gt;terms WHERE `term_id`=%d", $cat_id);
      $cat_name = $wpdb-&gt;get_var($sql);
 
      echo '<p>';
      echo '<h3><a href="'. get_category_link($cat_id) . '">' . $cat_name . '</a></h3>';
 
      // query all the posts for each cat
      query_posts(sprintf("cat=%d&amp;showposts=%d", $cat_id, $num_of_posts));
 
      // the loop
      if (have_posts()) :
          echo "<ul>";
          while(have_posts()) : the_post();
  ?&gt;
              <li><a title="&lt;?php the_title_attribute(); ?&gt;" href="&lt;?php the_permalink() ?&gt;" rel="bookmark"><?php the_title(); ?></a>
  <?php  
          endwhile;
          echo '<li><a href="'. get_category_link($cat_id) . '">(more)</a></li>';
          echo "</ul>";
      endif;
      echo "</p>";
    }
}
 
?>
</li></ul>