Php 用户密码重置功能

我试图在php网站上实现一个更改密码的功能。其想法是，其详细信息存储在数据库中的注册成员可以更改其密码，方法是先输入旧密码，然后再输入新密码两次。完成后，他们单击更改密码。但是，当单击此按钮时，屏幕上会显示“查询未工作”，这使我认为数据库连接下的“$Query”有问题。有人能帮我吗

 <?php

 session_start();


 $user = $_SESSION['dohare11'];

if ($user)
{
    if ($_POST['submit'])
{
 //check fields


    $oldpassword = md5($_POST['oldpassword']);
    $newpassword = md5($_POST['newpassword']);
    $repeatnewpassword = md5($_POST['repeatnewpassword']);
          //check password against db
    include("../connection/conn.php");

    $query = "SELECT password FROM cityfestusers WHERE username='$user'";
    mysqli_query($conn, $query) or die("Query didn't work");
    $row = mysqli_fetch_assoc($query);

    $oldpassworddb = $row['password'];


    //check passwords
    if ($oldpassword == $oldpassworddb) {
        //check new passwords
        if ($newpassword == $repeatnewpassword) {
            //success
            //change password in db
            $change = "UPDATE cityfestusers SET password='$newpassword' WHERE username='$user'";
            mysqli_query($conn, $change);
            session_destroy();
            die("Your password has been changed. <a href='index.php'>Return</a> to the main menu");

          } else {
            die("New passwords don't match");
           }
         } else {
              die("Old password doesnt match!");
           }
      }        
   else
    {


    }
    echo"

     <form action='changepassword.php' method='POST'>
     Old Password: <input type='text' name='oldpassword'><p>
     New Password: <input type='password' name='newpassword'><br>
     Repeat New Password: <input type='password' name='repeatnewpassword'><br>
     <input type='submit' name='submit' value='Change Password'>
     </form>
              ";
          }

    //check passwords
    if ($oldpassword == $oldpassworddb) {
        //check new passwords
        if ($newpassword == $repeatnewpassword) {
            //success
            //change password in db
            $update = "UPDATE cityfestusers SET password='$newpassword' WHERE username='$user'";
           $result = mysqli_query($conn, $update);
           $row = mysqli_fetch_assoc($result);
            session_destroy();
            die("Your password has been changed. <a href='index.php'>Return</a> to the main menu");

        } else {
            die("New passwords don't match");
        }
    } else {
        die("Old password doesnt match!");
    }
}        

//检查密码
如果（$oldpassword==$oldpassworddb）{
//检查新密码
如果（$newpassword==$repeatnewpassword）{
//成功
//更改数据库中的密码
$update=“update cityfestusers SET password='$newpassword'，其中username='$user'；
$result=mysqli_查询（$conn，$update）；
$row=mysqli\u fetch\u assoc（$result）；
会话_destroy（）；
die（“您的密码已更改。转到主菜单”）；
}否则{
死亡（“新密码不匹配”）；
}
}否则{
死（“旧密码不匹配！”）；
}
}        

否则 {

根据您需要在执行

mysqli\u查询后存储
结果
：

$result = mysqli_query($conn, $query);

如果结果对象

有数据，则应该对其进行任何进一步的处理。阅读本文档并执行与之相关的每个步骤

此外，是的，您的查询已失败：

echo 'Start with true'.PHP_EOL;

(true) or die('message1');

echo 'Start with false'.PHP_EOL;

(false) or die('message2');

给出：

Start with true
Start with false
message2

---

您可以从使用准备好的语句see开始，也许问题可以通过添加$row=mysqli\u fetch\u assoc（$result）来解决；

Start with true
Start with false
message2