+ $post_fields = array_filter( compact( array( 'post_author', 'post_name', 'post_parent', 'post_status', 'post_type', ) ) );
+ if ( ! empty( $post_fields ) ) {
+ $join = "JOIN $wpdb->posts ON $wpdb->posts.ID = $wpdb->comments.comment_post_ID";
+ foreach( $post_fields as $field_name => $field_value )
+ $where .= $wpdb->prepare( " AND {$wpdb->posts}.{$field_name} = %s", $field_value );
+ }
+