例如，使用posts_where 滤器如果需要使用posts_clauses 过滤，然后交换$where 具有$pieces 和设置$pieces[\'where\'] .= 而不是$where .=. 把它放到你的函数中。php文件，并在查询帖子之前添加一些条件标记。

function filter_where( $where ) 
{
    // Add some conditionals and abort if they\'re not met:
    // @example Abort on pages
    if ( ! is_page() )
        return;

    // posts in the last 30 days
    // $where .= " AND post_date > \'".date( \'Y-m-d\', strtotime( \'-30 days\' ) )."\'";

    // posts  30 to 60 days old
    // $where .= " AND post_date >= \'".date( \'Y-m-d\', strtotime( \'-60 days\' ) )."\'"." AND post_date <= \'".date( \'Y-m-d\', strtotime( \'-30 days\' ) )."\'";

    // posts between 01.03.2012 and 21.03.2012
    $where .= " AND post_date >= \'2012-03-01\' AND post_date <= \'2012-03-21\'";

    return $where;
}
add_filter( \'posts_where\', \'filter_where\' );

<section id="content">
<?php 
query_posts( array( \'post_type\' => array( \'post\', \'twentyyearsago\' ) ) ); 
if ( have_posts() )
{
while ( have_posts() )
{
    the_post();

    if ( \'twentyyearsago\' === get_post_type() ) // FIX THIS: strict type checking with "==="
    {
    ?>
        <article class="twentyyears">
            <h2><a href="<?php the_permalink() ?>" rel="bookmark" title="This day 20 years ago">This day 20 years ago</a></h2>
            <?php the_content(); ?>
            <footer><?php the_time( \'F j, Y\' );?></footer> // FIX THIS: One leading "<" in front of "<?php" too much
        </article>
    <?php } else { ?>
        <article class="post">
            <h2><a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>"><?php the_title(); ?></a></h2>
            <?php the_content(); ?>
            <footer><?php the_time( \'F j, Y\' ); ?></footer>
        </article>

    <?php 
    } // FIX THIS: one trailing ";" too much
} // endwhile;
else
{
    // do stuff
    echo "No Posts.";
} // endif; 
wp_reset_query(); 
?>
</section>