文章编辑页面的效果如下，被放置在了右侧底部。

/**
 * Calls the class on the post edit screen.
 */
function set_recommend() {
	new recommended();
}
if ( is_admin() ) {
	add_action( 'load-post.php', 'set_recommend' );
	add_action( 'load-post-new.php', 'set_recommend' );
}
/**
 * The Class.
 */
class recommended {
	/**
	 * Hook into the appropriate actions when the class is constructed.
	 */
	public

	function __construct() {
		add_action( 'add_meta_boxes', array( $this, 'recommend_box' ) );
		add_action( 'save_post', array( $this, 'save_recommend' ) );
	}
	/**
	 * Adds the meta box container.
	 */
	public

	function recommend_box( $post_type ) {
		// Limit meta box to certain post types.
		$post_types = array( 'the_post_types' );

		if ( in_array( $post_type, $post_types ) ) {
			add_meta_box(
				'recommend_option',
				__( 'Recommend option', 'textdomain' ),
				array( $this, 'render_recommend_box' ),
				$post_type,
				'side',
				'low'
			);
		}
	}
	/**
	 * Save the meta when the post is saved.
	 *
	 * @param int $post_id The ID of the post being saved.
	 */
	public

	function save_recommend( $post_id ) {

		/*
		 * We need to verify this came from the our screen and with proper authorization,
		 * because save_post can be triggered at other times.
		 */

		// Check if our nonce is set.
		if ( !isset( $_POST[ 'myplugin_inner_custom_box_nonce' ] ) ) {
			return $post_id;
		}
		$nonce = $_POST[ 'myplugin_inner_custom_box_nonce' ];

		// Verify that the nonce is valid.
		if ( !wp_verify_nonce( $nonce, 'myplugin_inner_custom_box' ) ) {
			return $post_id;
		}

		/*
		 * If this is an autosave, our form has not been submitted,
		 * so we don't want to do anything.
		 */
		if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) {
			return $post_id;
		}
		// Check the user's permissions.
		if ( 'page' == $_POST[ 'post_type' ] ) {
			if ( !current_user_can( 'edit_page', $post_id ) ) {
				return $post_id;
			}
		} else {
			if ( !current_user_can( 'edit_post', $post_id ) ) {
				return $post_id;
			}
		}
		/* OK, it's safe for us to save the data now. */

		// Sanitize the user input.
		$rec_data = sanitize_text_field( $_POST[ 'rec_item' ] );

		// Update the meta field.
		update_post_meta( $post_id, '_my_meta_value_key_rec', $rec_data );
	}

	/**
	 * Render Meta Box content.
	 *
	 * @param WP_Post $post The post object.
	 */
	public

	function render_recommend_box( $post ) {

		// Add an nonce field so we can check for it later.
		wp_nonce_field( 'myplugin_inner_custom_box', 'myplugin_inner_custom_box_nonce' );

		// Use get_post_meta to retrieve an existing value from the database.
		$value_rec = get_post_meta( $post->ID, '_my_meta_value_key_rec', true );

		// Checking for coupon active option.
		if ( $value_rec ) {
			if ( checked( '1', $value_rec, false ) )
				$active = checked( '1', $value_rec, false );
		}
		?>
		<ul class="rec_items">
			<li>
				<label for="rec_item">
					<input type="checkbox" id="rec_item" name="rec_item" value="1" <?php echo $active ?> /> Recommend it.
				</label>
			
			</li>
		</ul>
		<?php
	}
}

需要进行查询的地方添加下列两个条件即可：
如：
meta_key=_my_meta_value_key_rec
meta_value=1

query_posts($query_string . '&post_type=the_post_type&orderby=date&showposts=5&meta_key=_my_meta_value_key_rec&meta_value=1')