Resetting Queries in WordPress
If you run a custom query in WordPress, you must reset the query so that it does not affect subsequent behavior. In particular, if you use query_posts orthe_posts, this can cause problems with other queries or loops on the page if not reset correctly.
In the case of query_posts
query_posts overrides the main WordPress query, so you must always use wp_reset_query to reset the query after using it.
query_posts('cat=1&posts_per_page=5');
if (have_posts()) :
while (have_posts()) : the_post();
// display content
endwhile;
endif;
wp_reset_query();The case of the_post
Using the_post changes the global $post object. Therefore, after the_post, the post data must be reset using wp_reset_postdata.
$query = new WP_Query('cat=1&posts_per_page=5');
if ($query->have_posts()) :
while ($query->have_posts()) : $query->the_post();
// display content
endwhile;
wp_reset_postdata();
endif;Conclusion.
When customizing a WordPress query, it is important to reset it properly so that it does not affect subsequent behavior. In particular, if you use query_posts orthe_post, do not forget to perform the reset.