<div class="codebody" id="code81235">
<?PHP
//插入连接数据库的相关信息
require_once 'connectvars.PHP';
//开启一个会话
session_start();
$error_msg = "";
//如果用户未登录，即未设置$_SESSION['user_id']时，执行以下代码
if(!isset($_SESSION['user_id'])){
if(isset($_POST['submit'])){//用户提交登录表单时执行如下代码
$dbc = MysqLi_connect(DB_HOST,DB_USER,DB_PASSWORD,DB_NAME);
$user_username = MysqLi_real_escape_string($dbc,trim($_POST['username']));
$user_password = MysqLi_real_escape_string($dbc,trim($_POST['password']));
if(!empty($user_username)&&!empty($user_password)){
//MysqL中的SHA()函数用于对字符串进行单向加密
$query = "SELECT user_id,username FROM mismatch_user WHERE username = '$user_username' AND "."password = SHA('$user_password')";
$data = MysqLi_query($dbc,$query);
//用用户名和密码进行查询，若查到的记录正好为一条，则设置SESSION和COOKIE，同时进行页面重定向
if(MysqLi_num_rows($data)==1){
$row = MysqLi_fetch_array($data);
$_SESSION['user_id']=$row['user_id'];
$_SESSION['username']=$row['username'];
setcookie('user_id',$row['user_id'],time()+(60602430));
setcookie('username',$row['username'],time()+(60602430));
$home_url = 'loged.PHP';
header('Location: '.$home_url);
}else{//若查到的记录不对，则设置错误信息
$error_msg = 'Sorry,you must enter a valid username and password to log in.';
}
}else{
$error_msg = 'Sorry,you must enter a valid username and password to log in.';
}
}
}else{//如果用户已经登录，则直接跳转到已经登录页面
$home_url = 'loged.PHP';
header('Location: '.$home_url);
}
?>

Msimatch - Log In

<?PHP
if(!isset($_SESSION['user_id'])){
echo '<p class="error">'.$error_msg.'

';
?>

<form method = "post" action="<?php echo $_SERVER['PHP_SELF'];?>">

Log In

<label for="username">Username:
<input type="text" id="username" name="username"
value="<?php if(!empty($user_username)) echo $user_username; ?>" />


<label for="password">Password:
<input type="password" id="password" name="password"/>

<input type="submit" value="Log In" name="submit"/>

<?PHP
}
?>