PHP session application example login verification_PHP tutorial

复制代码 代码如下:

用户名：
密码：
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复制代码 代码如下:

@mysql_connect("localhost", "root","1981427") //选择数据库之前需要先连接数据库服务器
or die("数据库服务器连接失败");
@mysql_select_db("test") //选择数据库mydb
or die("数据库不存在或不可用");
//获取用户输入
$username = $_POST['username'];
$passcode = $_POST['passcode'];
//执行SQL语句获得Session的值
$query = @mysql_query("select username, userflag from users "
."where username = '$username' and passcode = '$passcode'")
or die("SQL语句执行失败");
//判断用户是否存在，密码是否正确
if($row = mysql_fetch_array($query))
{
session_start(); //标志Session的开始
//判断用户的权限信息是否有效，如果为1或0则说明有效
if($row['userflag'] == 1 or $row['userflag'] == 0)
{
$_SESSION['username'] = $row['username'];
$_SESSION['userflag'] = $row['userflag'];
echo "欢迎登录，点击此处进入欢迎界面";
}
else //如果权限信息无效输出错误信息
{
echo "用户权限信息不正确";
}
}
else //如果用户名和密码不正确，则输出错误
{
echo "用户名或密码错误";
}
?>

复制代码 代码如下:

unset($_SESSION['username']);
unset($_SESSION['passcode']);
unset($_SESSION['userflag']);
echo "注销成功";
?>

复制代码 代码如下:

session_start();
if(isset($_SESSION['username']))
{
@mysql_connect("localhost", "root" ,"1981427") //You need to connect to the database server before selecting the database
or die("Database server connection failed");
@mysql_select_db("test") //Select the database mydb
or die( "Database does not exist or is unavailable");
//Get Session
$username = $_SESSION['username'];
//Execute SQL statement to obtain the value of userflag
$query = @ mysql_query("select userflag from users "
."where username = '$username'")
or die("SQL statement execution failed");
$row = mysql_fetch_array($query);
//Compare the permission information in the current database with the information in the Session, and update the Session information if they are different
if($row['userflag'] != $_SESSION['userflag'])
{
$_SESSION['userflag'] = $row['userflag'];
}
//Output different welcome messages according to the value of Session
if($_SESSION['userflag'] = = 1)
echo "Welcome administrator".$_SESSION['username']."Log in to the system";
if($_SESSION['userflag'] == 0)
echo "Welcome user" .$_SESSION['username']."Log in to the system";
echo "Logout";
}
else
{
echo "You do not have permission to access this page";
}
?>

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