在login.php中输入成功的用户名和密码之前，不断出现错误消息

Question

以下是我正在开发的网站的代码：

1) login.php

​

<?php
session_start();
include("connection.php");

// username and password sent from form 
$myusername = (isset($_POST['myusername']) ? $_POST['myusername'] : null);
$mypassword = (isset($_POST['mypassword']) ? $_POST['mypassword'] : null); 


// To protect MySQL injection
$myusername = stripslashes($myusername); 
$mypassword = stripslashes($mypassword); 
$myusername = mysql_real_escape_string($myusername); 
$mypassword = mysql_real_escape_string($mypassword); 

$qry = "SELECT * FROM user WHERE user_name ='$myusername' AND user_password = '$mypassword'";
$result = mysql_query($qry);
$count = mysql_num_rows($result);

$output = mysql_fetch_assoc($result);

// If result matched $myusername and $mypassword, table row must be 1 row
      if($count == 1) {
         $_SESSION['login_user'] = $myusername;
         $_SESSION['mypassword'] = $mypassword;
         header("location: foodline.php");
         exit();
      }
      else {
         echo "Invalid Username or Password";
      }
?>


<html>
   
   <head>
      <title>Login Page</title>
      
      <style type = "text/css">
         body {
            font-family:Arial, Helvetica, sans-serif;
            font-size:14px;
         }
         
         label {
            font-weight:bold;
            width:100px;
            font-size:14px;
         }
         
         .box {
            border:#666666 solid 1px;
         }
      </style>
      
   </head>
   
   <body bgcolor = "#FFFFFF">
	
      <div align = "center">
         <div style = "width:300px; border: solid 1px #333333; " align = "left">
            <div style = "background-color:#333333; color:#FFFFFF; padding:3px;"><b>Login</b></div>
				
            <div style = "margin:30px">
               
               <form action = "" method = "post">
                  <label>UserName  :</label><input type = "text" name = "username" class = "box"/><br /><br />
                  <label>Password  :</label><input type = "password" name = "password" class = "box" /><br/><br />
                  <input type = "submit" value = " Submit "/><br />
               </form>					
            </div>
				
         </div>
			
      </div>

   </body>
</html>

​

2) connection.php

​

<?php
$mysql_hostname ="localhost";
$mysql_user = "root";
$mysql_password ="";
$mysql_database = "foodline";

mysql_connect("$mysql_hostname", "$mysql_user", "$mysql_password") or die("Could not connect database");
mysql_select_db("$mysql_database") or die("Could not connect the database".mysql_error());
?>

​

3) session.php

​

<?php
   include('connection.php');
   session_start();
   
   $user_check = $_SESSION['login_user'];
   
   $ses_sql = mysql_query($user_check);
   
   $row = mysql_fetch_array($ses_sql);
   
   $login_session = $row['username'];
   
   if(!isset($_SESSION['login_user']))
   {
      header("location:foodline.php");
   }
?>

​

4)这是我得到的输出屏幕：Output Screen

错误信息‘无效的用户名或密码’不会从上面的代码中删除。我遗漏了什么或者在代码上做了什么额外的事情？

请帮帮我!

Answer 1

如果您的表单已经提交，您可能只希望执行PHP部分。使用isset。

用这个更新你的php。

<?php
session_start();
include("connection.php");

if(isset($_POST['submit']))
{
    // username and password sent from form 
    $myusername = (isset($_POST['myusername']) ? $_POST['myusername'] : null);
    $mypassword = (isset($_POST['mypassword']) ? $_POST['mypassword'] : null); 


    // To protect MySQL injection
    $myusername = stripslashes($myusername); 
    $mypassword = stripslashes($mypassword); 
    $myusername = mysql_real_escape_string($myusername); 
    $mypassword = mysql_real_escape_string($mypassword); 

    $qry = "SELECT * FROM user WHERE user_name ='$myusername' AND user_password = '$mypassword'";
    $result = mysql_query($qry);
    $count = mysql_num_rows($result);

    $output = mysql_fetch_assoc($result);

    // If result matched $myusername and $mypassword, table row must be 1 row
          if($count == 1) {
             $_SESSION['login_user'] = $myusername;
             $_SESSION['mypassword'] = $mypassword;
             header("location: foodline.php");
             exit();
          }
          else {
             echo "Invalid Username or Password";
          }
}
?>

现在，您的php只有在表单已经提交时才会执行。

更新

"SELECT * FROM user WHERE user_name ='" . $myusername . "' AND user_password = '" . $mypassword . "'";