PHP-登入次数问题，出现Trying to get property of non-object

发布于 2016-12-29 11:52:18 字数 2513 浏览 1159 评论 1

要设计个网页(login_process.php)重另外一个网页(login.php)获得资料，避免有人不断重复登入，3次登入则导向注册页面(register.php), 但是现在我在login_process.php的第27行出现 Trying to get property of non-object这个错误，有人能告诉我这是为什么吗？
以下是我的login_process.php的代码:

<?php
    $conn = mysql_connect("localhost", "root", "");
    if(!$conn){
        die('Could not connect'. mysql_error());
    }
    mysql_select_db("logindb", $conn);
    
    if(isset($_POST['Submit'])){
        if(empty($_POST['Username']) || empty($_POST['Password'])){
            echo "You should fill in all the forms before you submit!";
            exit;
        }
        
        $username = $_POST['Username'];
        $password = $_POST['Password'];
        $attempts = $_POST['login'];
        
        $query = "SELECT username, password FROM `logint` WHERE username='$username' and password='$password'";
        $result = mysql_query($query);
        
        if(!$result){
            // Cannot connect to mysql
            echo "The query failed " . mysql_error();
        } else {
            // Connect to mysql
            $row = mysql_num_rows($result);
                if($row['username'] != $username && $row['password'] != $password) {
                    if(isset($_POST['login'])){
                        if($_POST['login'] <= 3){
                        // Less than 3 attempts
                            $attempts = $_POST['login'] + 1;
                            echo 'You had made $attempts times error, please try again. (Maximum 3 times)';
                            ?>
                                <form name="login_process" method="post" action="login.php">
                                    <input type = "hidden" name = "">
                                </form>
                            <?php
                        } else {
                        // More than 3 attempts
                            ?>
                                <script type="text/javascript">
                                    alert("You had made more than 3 times wrong, PLEASE Register first!"); 
                                </script>
                            <?php
                            header('location:register.php');
                        }
                    }
                }
        }
    }