309c309
<         $sqlcat = '';
---
>         $join = '';
311c311,317
<             $sqlcat = " AND post_category = '$current_category' ";
---
> 		$join = " INNER JOIN $wpdb->post2cat ON $wpdb->posts.ID = $wpdb->post2cat.post_id ";
> 		$cat_array = $wpdb->get_col("SELECT category_id FROM $wpdb->post2cat WHERE post_id = $post->ID");
> 		$join .= " AND ($wpdb->post2cat.category_id = " . intval($cat_array[0]);
> 		for ($i = 1; $i < (count($cat_array)); $i++) {
> 			$join .= ' OR category_id = ' . intval($cat_array[$i]);
> 		}
> 		$join .= ')';
344c350
<         $sqlcat = '';
---
>         $join = '';
346c352,358
<             $sqlcat = " AND post_category='$current_category' ";
---
> 		$join = " INNER JOIN $wpdb->post2cat ON $wpdb->posts.ID= $wpdb->post2cat.post_id ";
> 		$cat_array = $wpdb->get_col("SELECT category_id FROM $wpdb->post2cat WHERE post_id = $post->ID");
> 		$join .= ' AND (category_id = ' . intval($cat_array[0]);
> 		for ($i = 1; $i < (count($cat_array)); $i++) {
> 			$join .= ' OR category_id =  ' . intval($cat_array[$i]);
> 		}
> 		$join .= ')';
362c374
<         $nextpost = @$wpdb->get_row("SELECT ID,post_title FROM $wpdb->posts WHERE post_date > '$current_post_date' AND post_date_gmt < '$now' AND post_status = 'publish' $sqlcat $sql_exclude_cats AND ID != $post->ID ORDER BY post_date ASC LIMIT $limitnext,1");
---
>         $nextpost = @$wpdb->get_row("SELECT ID,post_title FROM $wpdb->posts $join WHERE post_date > '$current_post_date' AND post_date_gmt < '$now' AND post_status = 'publish' $sqlcat $sql_exclude_cats AND ID != $post->ID ORDER BY post_date ASC LIMIT $limitnext,1");
506c518
< ?>
\ No newline at end of file
---
> ?>