displaying posts from a single category in sidebar

43 minutes later i found the answer here:

ok i got this code in the side bar BUT its no good if the main post is in more than one catagory, where catagory name is i need it to show ALL the catgorys for the post that has been selected

<?php global $post; $categories = get_the_category();foreach ($categories as $category) : ?>
<h2>&raquo; <?php echo $category->name; ?></h2>
<ul class="rightcol">
<?php $posts = get_posts('numberposts=20&amp;category='. $category->term_id);foreach($posts as $post) :?>
<li><span class="threecolsmall"><?php the_time('j M y') ?></span><br />
<a href='<?php the_permalink() ?>'><?php the_title(); ?></a></li>
<?php endforeach; ?>
<li><strong><a href="<?php echo get_category_link($category->term_id);?>" title="View all posts filed under <?php echo $category->name; ?>">ARCHIVE FOR '<?php echo $category->name; ?>' CATEGORY &raquo;</a></strong></li>
<?php endforeach; ?>
</ul>

I have made changes in the above code, find the same. I think it works for you:

<?php global $post; $categories = get_the_category();foreach ($categories as $category) : ?>
<h2>&raquo; <?php echo $category->name; ?></h2>
<ul class="rightcol">

<?php
//Code added for getting all categories in a variable $cat_ids
foreach((get_the_category()) as $category) {
	$cat_ids=$cat_ids . $category->cat_ID . ',';
}
$cat_ids=substr($cat_ids, 0, -1);
//----------
?>

<?php $posts = get_posts('numberposts=20&amp;category='. $cat_ids);foreach($posts as $post) : //replaced $category->term_id with $cat_ids ?>
<li><span class="threecolsmall"><?php the_time('j M y') ?></span><br />
<a href='<?php the_permalink() ?>'><?php the_title(); ?></a></li>
<?php endforeach; ?>
<li><strong><a href="<?php echo get_category_link($category->term_id);?>" title="View all posts filed under <?php echo $category->name; ?>">ARCHIVE FOR '<?php echo $category->name; ?>' CATEGORY &raquo;</a></strong></li>
<?php endforeach; ?>
</ul>

hi, further to this idea i have the problem if the post is in one or more category it displays a list within a list, ideally i just want to show all the catagories the post is in but ONLY the other posts in the catagory it was selected…hope that makes sense!

<?php global $post; $categories = get_the_category();foreach ($categories as $category) : ?>
<h2>&raquo; <?php echo $category->name; ?></h2>
<p><?php _e('Category: ', 'blank'); ?><?php the_category(', ') ?></p>
<ul class="rightcol">
<?php $posts = get_posts('numberposts=20&amp;category='. $category->term_id);foreach($posts as $post) :?>
<li><span class="threecolsmall"><?php the_time('j M y') ?></span><br />
<a href='<?php the_permalink() ?>'><?php the_title(); ?></a></li>
<?php endforeach; ?>
<!--<li><strong><a href="<?php echo get_category_link($category->term_id);?>" title="View all posts filed under <?php echo $category->name; ?>">ARCHIVE FOR '<?php echo $category->name; ?>' CATEGORY &raquo;</a></strong></li>-->
<?php endforeach; ?>
</ul>

.. sorry i ment more than one category, if its just one its not a problem!

is there a way I can display a sub category and not the parent category….