由于您没有说明要实现什么，并且刚刚提到需要获取相关数据。有两个选项可以查询自定义表：

迭代帖子时，需要使用post对象中的post id单独执行自定义查询

 <?php 
      function populate_posts_data( $posts, $query ) {
           global $wpdb;

           if ( !count( $posts ) ) 
               return $posts;  // posts array is empty send it back with thanks.

           while ( $posts as $post ) {
               // query to get custom post data from custom table
               $query = "SELECT * FROM {$wpdb->prefix}my_plugin_table WHERE post_id={$post->ID}";
               $results = $wpdb->get_results( $query );
           }
           return $posts;
       }
       add_filter( \'the_posts\', \'populate_posts_data\' );
 ?>