既然HTTP是无状态协议，mysql_close还有必要么？
既然是查一次连接一次，为什么还要关闭连接呢？
还有上传图片，有个imagedestroy函数释放内存，如果我不释放呢，机器内存就一直傻乎乎让图片占着直到死机吗？
------解决方案--------------------
你的网站的访问者(他的电脑或手机)和你的web server(比如apache)之间的连接是http,
mysql_connect建立的是你的web server和你的mysql server之间的连接(即使它们在一个机器上)
如果忘记关闭数据库连接, 该连接会保持直到你close了或者该次请求的php运行完毕...
如果没有imagedestroy, 该内存会被占用直到你destroy或者运行结束.(我不明确会不会被垃圾回收,如果该图片的资源引用数为0)
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