我在这个网站上搜索过,看不到任何明显我做错的事情,但我的查询不起作用并返回警告:mysql_fetch_array() 期望参数 1 是资源, 错误给出的布尔值
$sql2 = "SELECT users.user_id, users.username, users.profile, post_id, post_content, post_date, post_topic, post_by, topics.category, topic.sub_category
FROM `posts`
JOIN `users` on posts.post_by = users.user_id WHERE post_topic='$id'
JOIN `topics` on posts.post_topic = topics.topic_id";