无法从PHP中的mysql_fetch_array（）获取数据

Question

这是我的PHP :(该代码能够很好地完成工作）

if(isset($_COOKIE["user"])) {
$username = $_COOKIE["user"]; 
$pass = $_COOKIE["password"];
$check = mysql_query("SELECT * FROM members WHERE email = '$username'")or die(mysql_error()); 
    while ($info = mysql_fetch_array( $check ))
        {
        //if the cookie is present but has the wrong password, they are  taken to the login page 
        if ($pass != $info['password']) 
        {
            header("Location: login.php"); 
            exit();
        }  
        else //if the cookie is present and doesn'T have the wrong password they are shown the admin area    
        { 
            include 'header.php';
        }
    }

}
else //if the cookie is present and doesn'T have the wrong password they are shown the admin area    
        {
            header("Location: login.php"); 
            exit();
        }   

但稍后在同一页面上，我尝试从$ info变量访问数据，但没有任何结果。我知道我做错了什么，但无法弄清楚是什么......

<?php print $info['name']?>

如果我将变量设为全局变量，我该如何使用它？

$check = mysql_query("SELECT * FROM members WHERE email = '$username'")or die(mysql_error());
$info = mysql_fetch_array( $check );
    while ($info.....???)
        {
                        }

Answer 1

当你这样做时：

while ($info = mysql_fetch_array( $check ))
{
   //
   // do things with info:
   //...
   //
}

当它超出最后一条记录时，最后的$ info为false（不再记录）。因此$ info为false，while循环终止，其中没有数据库“info”。

作为解决方法，我们会在 $ info0 中保存第一个$ info，

$info0 = false;

while ($info = mysql_fetch_array( $check ))
{
  if(! $info0)
  {
    $info0 = $info;
  }
   //
   // do things with info:
   //...
   //
}

在while循环后使用 $ info0 而不是$ info。

<?php echo $info0['name']; ?>

Answer 2

$ info变量已本地化为if语句。

将$ info变量设为全局。

Answer 3

在while循环后，使用mysql_data_seek函数：

$info = mysql_data_seek($check, 0) ? mysql_fetch_array($check) : null;

当然，you MUST avoid to use all PHP functions that begin with mysql_。

Answer 4

如果你想在$info中使用if(isset($_COOKIE["user"])) {是可以的，但是如果你想在$info之外使用if(isset($_COOKIE["user"])) {则会出现问题，因为$info没有初始化在if(isset($_COOKIE["user"])) {之前，所以你的代码就像这样

$username = $_COOKIE["user"]; 
$pass = $_COOKIE["password"];

if(isset($_COOKIE["user"])) {
$check = mysql_query("SELECT * FROM members WHERE email = '$username'")or die(mysql_error()); 
    while ($info = mysql_fetch_array( $check ))
        {
        //if the cookie is present but has the wrong password, they are  taken to the login page 
        if ($pass != $info['password']) 
        {
            header("Location: login.php"); 
            exit();
        }  
        else //if the cookie is present and doesn'T have the wrong password they are shown the admin area    
        { 
            include 'header.php';
        }
    }

}
else //if the cookie is present and doesn'T have the wrong password they are shown the admin area    
        {
            header("Location: login.php"); 
            exit();
        }   


$check = mysql_query("SELECT * FROM members WHERE email = '$username'")or die(mysql_error()); 
$info = mysql_fetch_array( $check );