INSERT INTO中断但获取数据有效吗？

Question

    <?php
/* Registration process, inserts user info into the database 
   and sends account confirmation email message
 */

// Set session variables to be used on profile.php page
$_SESSION['email'] = $_POST['email'];
$_SESSION['first_name'] = $_POST['firstname'];
$_SESSION['last_name'] = $_POST['lastname'];

// Escape all $_POST variables to protect against SQL injections
$first_name = $mysqli->escape_string($_POST['firstname']);
$last_name = $mysqli->escape_string($_POST['lastname']);
$email = $mysqli->escape_string($_POST['email']);
$password = $mysqli->escape_string(password_hash($_POST['password'], PASSWORD_BCRYPT));
$hash = $mysqli->escape_string( md5( rand(0,1000) ) );

// Check if user with that email already exists
$result = $mysqli->query("SELECT * FROM users WHERE email='$email'") or die($mysqli->error());

// We know user email exists if the rows returned are more than 0
if ( $result->num_rows > 0 ) {

    $_SESSION['message'] = 'User with this email already exists!';
    header("location: error.php");

}else { // Email doesn't already exist in a database, proceed...
    require 'db.php';
    // active is 0 by DEFAULT (no need to include it here)
    $sql = "INSERT INTO users (first_name, last_name, email, password, hash) VALUES ('$first_name', '$last_name','$email','$password','$hash')";    

    // Add user to the database
    if ( $mysqli->query($sql) ){

        $_SESSION['active'] = 0; //0 until user activates their account with verify.php
        $_SESSION['logged_in'] = true; // So we know the user has logged in
        $_SESSION['message'] = "Confirmation link has been sent to $email, please verify your account by clicking on the link in the message!";

        // Send registration confirmation link (verify.php)
        $to      = $email;
        $subject = 'Account Verification ( The Care Company )';
        $message_body = '
        Hello '.$first_name.',

        Thank you for signing up!

        Please click this link to activate your account:

        http://localhost/home/d6wo7cb6ehdx/public_html/verify.php?email='.$email.'&hash='.$hash;  

        mail( $to, $subject, $message_body );

        header("location: profile.php"); 

    }else {
        $_SESSION['message'] = 'Registration failed!';


        header("location: error.php");
    }

}

从上面的i代码中您可以看到，我正在尝试将此数据插入数据库中（只要该人已经完成。

目前对我来说没有任何意义的事实是，当我尝试与数据库中已有的成员进行注册时，它会回来说明这种情况，但是如果我尝试以一个新用户，只是一直说“注册失败”

有什么帮助吗？