Question

因此，在'index.php'中，用户将他们的用户名和密码输入到HTML输入中，并将它们保存为'$ username'和'$ password'。那么PHP说：

<?php 
$loginquery = mysqli_query($connection,"SELECT * FROM users WHERE username = '$username' AND password = '$password'"); 
$user = mysqli_fetch_array($loginquery); 
session_start(); 
$_SESSION['username'] = $user['username']; 
echo $_SESSION['username']; 
?> 

它呼应的出“$ _SESSION [”用户名“]”好了，但如果我然后去“home.php”它没有实际保存的变量，它说“注意：未定义的变量：_SESSION在/Applications/XAMPP/xamppfiles/htdocs/tobyscott/home.php上线24'

这实在是烦我！谢谢:)

Answer 1

你有一个在session_start（）;声明在你的home.php中 - 或者它在那里失踪？

Answer 2

听起来像你使用提交给自己的脚本。

添加一个条件，以确保表单处理逻辑只能运行GET/POST提交：

if(!empty($_POST[ 'varname' ])) 
{ 
    // Logic 
    $loginquery = mysqli_query($connection,"SELECT * FROM users WHERE username = '$username' AND password = '$password'"); 
    $user = mysqli_fetch_array($loginquery); 
    session_start(); 
    $_SESSION['username'] = $user['username']; 
    echo $_SESSION['username']; 
} 

OR：

if(!empty($_GET[ 'varname' ])) 
{ 
    // Logic 
    $loginquery = mysqli_query($connection,"SELECT * FROM users WHERE username = '$username' AND password = '$password'"); 
    $user = mysqli_fetch_array($loginquery); 
    session_start(); 
    $_SESSION['username'] = $user['username']; 
    echo $_SESSION['username']; 
}