Php 页面在重新加载后变为空白

无法理解在重新加载成员页面（登录后）后，页面变为空白。但所有其他事情都在正常工作

下面是登录表单页面之后的login_execution.php页面的代码

<?php

session_start();
$con=mysql_connect("localhost","root","");
if (!$con) {
    die('Could not connect: ' . mysql_error());
}
$db_selected = mysql_select_db('loged', $con);
if(isset($_POST["submit"])) {
$username=mysql_real_escape_string($_POST['username']); 
$password=mysql_real_escape_string($_POST['password']); 
$password=md5($password); 
 $sql="SELECT username FROM  list WHERE username='$username' and password='$password'";
$result=mysql_query($sql);
$count=mysql_num_rows($result);


if($count==1)
{
session_regenerate_id();
    $_SESSION['username'] = $username;
    $_SESSION['password'] = $password;
    session_write_close();
    echo "<table>
<tr>
<th>username</th>";



     $row = mysql_fetch_array($result) 

    ?>
  <tr style="background-color:blue;color:white;"> 
          <td><font size="6"><?php echo $row['username']; ?></font></td>
          <h1 align="center"><font size="6" color="blue">welcome <?php echo $row['username']; ?></font></h1>
          <p align="right"><font size="4" color="#380B61"><a href="logout.php">Logout</a></font></td>





        </tr>
          <?php


echo "</table>";
}

else 
{
?> 
<h1 align="center"><font size="4" color="red">enter coerrect username and password</font></h1>
<td><a href="login.php">BACK</a></td>
<?php
}
}
?>

欢迎

输入正确的用户名和密码

您的条件是，如果在重新加载页面时单击“提交”，则不会单击“提交”按钮，因此不会显示任何内容

要更正此问题，请使用下面的代码

<?php

session_start();
$con=mysql_connect("localhost","root","");
if (!$con) {
    die('Could not connect: ' . mysql_error());
}
$db_selected = mysql_select_db('loged', $con);
if(isset($_POST["submit"])) {
$username=mysql_real_escape_string($_POST['username']); 
$password=mysql_real_escape_string($_POST['password']); 
$password=md5($password); 
 $sql="SELECT username FROM  list WHERE username='$username' and password='$password'";
$result=mysql_query($sql);
$count=mysql_num_rows($result);

if($count==1)
{
$row = mysql_fetch_array($result)
session_regenerate_id();
    $_SESSION['username'] = $username;
    $_SESSION['password'] = $password;
    $_SESSION['name'] = $row['username'];
    session_write_close();
}
}


if(isset($_SESSION['username']))
{
   echo "<table>
<tr>
<th>username</th>";





    ?>
  <tr style="background-color:blue;color:white;"> 
          <td><font size="6"><?php echo $row['username']; ?></font></td>
          <h1 align="center"><font size="6" color="blue">welcome <?php echo $_SESSION['name']; ?></font></h1>
          <p align="right"><font size="4" color="#380B61"><a href="logout.php">Logout</a></font></td>





        </tr>
          <?php


echo "</table>";
}

else 
{
?> 
<h1 align="center"><font size="4" color="red">enter coerrect username and password</font></h1>
<td><a href="login.php">BACK</a></td>
<?php
}
?>

欢迎

输入正确的用户名和密码

这将是因为您正在检查是否单击了“提交”按钮，否则刷新后必须重定向到登录页面

<?php

session_start();
$con=mysql_connect("localhost","root","");
if (!$con) {
    die('Could not connect: ' . mysql_error());
}
$db_selected = mysql_select_db('loged', $con);
if(isset($_POST["submit"])) {
$username=mysql_real_escape_string($_POST['username']); 
$password=mysql_real_escape_string($_POST['password']); 
$password=md5($password); 
 $sql="SELECT username FROM  list WHERE username='$username' and password='$password'";
$result=mysql_query($sql);
$count=mysql_num_rows($result);


if($count==1)
{
session_regenerate_id();
    $_SESSION['username'] = $username;
    $_SESSION['password'] = $password;
    session_write_close();
    echo "<table>
<tr>
<th>username</th>";



     $row = mysql_fetch_array($result) 

    ?>
  <tr style="background-color:blue;color:white;"> 
          <td><font size="6"><?php echo $row['username']; ?></font></td>
          <h1 align="center"><font size="6" color="blue">welcome <?php echo $row['username']; ?></font></h1>
          <p align="right"><font size="4" color="#380B61"><a href="logout.php">Logout</a></font></td>





        </tr>
          <?php


echo "</table>";
}

else 
{
?> 
<h1 align="center"><font size="4" color="red">enter coerrect username and password</font></h1>
<td><a href="login.php">BACK</a></td>
<?php
}
}
else {
header("location:login.php");
}
?>

欢迎

输入正确的用户名和密码

只需检查您的post数据中是否有“提交”，以及回显您的sql查询并在数据库中运行它并检查它是否正确..是的，它工作正常，但重新编辑页面后，页面变为空白totalyok。。您已经为if添加了else（$count==1），只需为if添加else部分（isset（$\u POST[“submit”]）&回显一些内容&请参阅。。否则{？>请输入正确的用户名和密码