更新电子邮件地址后登录无效

Question

当用户使用电子邮件地址注册作为登录时，一切都很好，他可以注销并重新登录。问题是当他在他的个人资料中更新他的电子邮件地址时，他无法登录任何更长，使用新电子邮件或旧电子邮件，因为数据库反映了新电子邮件。

的login.php

<?php
    session_start();     
    if($_GET["logout"]==1 AND $_SESSION['id']) { session_destroy();
            header("Location:logout.php");      
    }

    include 'connection.php';    
    if ($_POST['submit']=="Sign Up") {  
        if (!$_POST['email']) $error.="<br />Please enter your email";
            else if (!filter_var($_POST['email'], FILTER_VALIDATE_EMAIL)) $error.="<br />Please enter a valid email address";           
        if (!$_POST['password']) $error.="<br />Please enter your password";
            else {          
                if (strlen($_POST['password'])<8) $error.="<br />Please enter a password with at least 8 characters";
                if (!preg_match('`[A-Z]`', $_POST['password'])) $error.="<br />Please enter at least 1 capital letter";         
            }

         if ($error) $error = "There were error(s) in your signup details:".$error;
         else {
            $query = "SELECT * FROM `users` WHERE email='".mysqli_real_escape_string($link, $_POST['email'])."'";
            $result = mysqli_query($link, $query);
            $results = mysqli_num_rows($result);
            if ($results) $error = "That email address is already registered";
            if ($results) $error = "That email address is already registered";
            else {
                $query="INSERT INTO `users` (`email`, `password`) VALUES('".mysqli_real_escape_string($link, $_POST['email'])."', '".md5(md5($_POST['email']).$_POST['password'])."')";
                mysqli_query($link, $query);
                $message = "You've been signed up!";
                $_SESSION['id']=mysqli_insert_id($link); 
                header("Location:registration.php");
            }
        }
    }

    if ($_POST['submit']=="Log In") {
        $query="SELECT * FROM `users` WHERE email='".mysqli_real_escape_string($link, $_POST['loginemail'])."' AND password='".md5(md5($_POST['loginemail']).$_POST['loginpassword'])."' LIMIT 1";
        $result = mysqli_query($link, $query);
        $row = mysqli_fetch_array($result);
        if ($row) {
            $_SESSION['id']=$row['id'];            
                header("Location:dashboard.php");
            } else {
                $loginerror = "We could not find a user with that email and password. Please try again.";            
            }
        }   
?>

profile.php

<?php
    session_start();
    error_reporting(E_ALL ^ E_NOTICE);      
    include("connection.php");
    $query = "SELECT * FROM `users` WHERE id='".$_SESSION['id']."' LIMIT 1";    
    $result = mysqli_query($link, $query);    
    $row = mysqli_fetch_array($result);                 
        $firstname = $row['firstname'];  $lastname = $row['lastname'];  $gender = $row['gender']; $contact = $row['contact'];  $email = $row['email'];  $password = $row['password'];
        $addressone = $row['addressone'];  $addresstwo = $row['addresstwo'];  $city = $row['city'];  $state = $row['state'];  $zip = $row['zip'];    
?>

<!-- Head -->
<?php include 'includes/head.php'; ?> 

    <form class="form-horizontal" id="registrationForm" method="post" action="insertregistration.php">

        <div class="center">
            <h4 class="text-center">My Profile</h4>
        </div>

    <br /><br />

        <div class="form-group">
            <label class="col-md-5 control-label" for="firstname">First Name</label>  
                <div class="col-md-2">
                    <input type="text" class="form-control input-md" name="firstname" readonly="readonly" value="<?php echo $firstname; ?>">
                </div>
        </div>

        <div class="form-group">
            <label class="col-md-5 control-label" for="lastname">Last Name</label>  
                <div class="col-md-2">
                    <input type="text" class="form-control input-md" name="lastname" readonly="readonly" value="<?php echo $lastname; ?>">
                </div>
        </div>  

        <div class="form-group">
            <label class="col-md-5 control-label" for="gender">Gender</label>
                <div class="col-md-1">
                    <select id="gender" name="gender" class="form-control" >
                        <option readonly="readonly" value="<?php echo $gender; ?>"><?php echo $gender; ?></option>
                    </select>
                </div>
        </div>

        <div class="form-group">
            <label class="col-md-5 control-label" for="contact">Phone Number</label>  
                <div class="col-md-2">
                    <input type="text" class="form-control input-md" name="contact" value="<?php echo $contact; ?>">
                </div>
        </div>

        <div class="form-group">
            <label class="col-md-5 control-label" for="email">Email Address</label>  
                <div class="col-md-2">
                    <input type="email" class="form-control input-md" name="email" value="<?php echo $email; ?>">
                </div>
        </div>  

        <div class="form-group">
            <label class="col-md-5 control-label" for="password">Password </label>
                <div class="col-md-2">
                    <input type="password" class="form-control input-md" name="password" value="<?php echo $password; ?>">
                </div>
                    <button input type="submit" class="btn btn-primary">Change Password</button>
        </div>

        <div class="text-center">
            <input type="submit" name="submit" class="btn btn-kani btn-lg" value="Update Profile"/>
        </div> 

    </form>