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HomeBackend DevelopmentPHP Tutorialmysql数据库只能被update一次吗?并且怎么让结果与字符串对比

php做的下载功能,完成的功能有:
1. 如果没有登录就跳转到登录界面
2. 下载计数

代码如下:(有3个问题写在代码注释中,非常感谢)

点击要下载的文件(一个链接)跳转到singledownload.php页面处理下载
&file_name=&file_id=' />

singledownload.php页面的代码

        $file_name = $_GET['file_name'];   //文件名(数据库中查找出来的)	$file_dir  = $_GET['file_dir'];      //文件路径(固定的)	$file_id = $_GET['file_id'];    //文件ID(数据库中查找出来的)		/*连接数据库*/	$link=mysql_connect("localhost","root","root"); 	mysql_select_db("wpgc", $link);	$q = "SELECT * FROM downloads WHERE file_id=" . $file_id;		mysql_query("SET NAMES UTF-8");	$rs = mysql_query($q, $link); //获取结果集	if(!$rs){	    die("无效结果集");	}		//权限检测	if ( !is_user_logged_in() ) { //如果没有登录	    if ( $row[10] == "2") { //检查文件权限‘2’的意思是登录后才能下载这个文件               //问题1:$row[]是什么?我没有在任何地方定义过,并且程序没有进入这里;但是在链接中$row[1]是成功的,我希望$row[]是数据库中存放的值	        echo "<script>window.location ='../../../login.php';</script>";           }	}	        /*计算下载次数*/	$downloadcount = $row[9];	$downloadcount = $downloadcount + 1;			$sql = "UPDATE downloads SET file_hits = " . $downloadcount . " WHERE file_id = " . $file_id;        //问题2:这里只能更新一次,第一次下载 更新file_hits字段从0变成1,之后再下载就不会变了	if(mysql_query($sql, $link)){	    	} else {	    	}        //问题3:这个if判断总是说找不到文件,但是将这个注释了以后文件的下载正常        if(!file_exists($file_dir.$file_name)){            echo "找不到 [" . $file_dir.$file_name . "] 文件";	    exit;	}else{            /*开始下载文件(这里很正常)*/		$file = fopen($file_dir.$file_name,"r");		Header("Content-type: application/octet-stream");		Header("Accept-Ranges: bytes");		Header("Accept-Length: ".filesize($file_dir.$file_name));		Header("Content-Disposition: attachment; filename=".$file_dir.$file_name);		echo fread($file, filesize($file_dir.$file_name));		$buffer=1024;		while (!feof($file)) {			$file_data=fread($file,$buffer);			echo $file_data;		}		fclose($file);


我是php新手 请多指教...


回复讨论(解决方案)

1、不是你写的代码吗,你自己不知道别人更不知道了。
2、打印一下各个值对不
3、路径不正确吧

1、不是你写的代码吗,你自己不知道别人更不知道了。
2、打印一下各个值对不
3、路径不正确吧
我是模仿别人写的,所以有很多疑问 大侠 .. 

模仿是没有用的
你需要知道是你想做什么

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