Show Categories not Pages

For the menu I want to show some main categories not pages, this is the current header code to show the pages:

<?php
        $menupages = $wpdb->get_results("SELECT ID, post_title FROM $wpdb->posts WHERE post_type = 'page' AND post_status = 'publish' AND post_parent = 0 ORDER BY menu_order ASC");
        $menupagesnumber = count($menupages);
		$menupagescount = 1;
		foreach ($menupages as $menupage) :
        ?>
	        <li
			<?php
			if (is_page($menupage->ID) && $menupagescount!=$menupagesnumber ) {
				echo ' id="current"';
			}
			if ($menupagescount==$menupagesnumber) {
				echo ' class="last"';
			}
			if (is_page($menupage->ID) && $menupagescount==$menupagesnumber) {
				echo ' id="lastcurrent"';
			}
			$menupagescount++;
			?>>
            <a href="<?php echo get_permalink($menupage->ID); ?>" title="<?php echo $menupage->post_title; ?>"><?php echo $menupage->post_title; ?></a></li>

		<?php endforeach; ?>

Whats changes are needed to get categories instead.