验证电子邮件尚未注册PHP Mysql

Question

Right now I am trying to set up a user registration page, and I've been having trouble with verifying that the e-mail is not already in use. I figured all I had to do was make a query to my database to check and see if the e-mail was already in use. This seems pretty straight forward, so I don't know why it's giving me such a problem.

I've read several posts, and tried several approaches with PDO and mysqli, but I have still yet to get this script to function properly. Any help would be greatly appreciated.

<?php
session_start();
if( isset($_SESSION['user_id']) ){
    header("Location: /");
}
require 'database.php';
$message = '';
if(!empty($_POST['email']) && !empty($_POST['password'])&& !empty($_POST['firstname'])&& !empty($_POST['lastname'])&& !empty($_POST['phone'])&& !empty($_POST['address'])&& !empty($_POST['city'])&& !empty($_POST['zip'])):

//check to see if e-mail is already being used
    //This method always says that the email is already in use, even if I am entering a new one. 
    /*
    $records = $conn->prepare('SELECT * FROM users WHERE email = :email');
    $records->bindParam(':email', $_POST['email']);
    $records->execute();
    $results = $records->fetch(PDO::FETCH_ASSOC);
    if( count($results) > 0){
        $message = "Sorry, that E-mail address is already registered to an account.";
    }
    */
    //this one never says that the email is in use.
    /*
    $email = $_POST['email'];
    $query = mysqli_query($conn, "SELECT * FROM users WHERE email='".$email."'");

    if(mysqli_num_rows($query) > 0){
        $message = "Sorry, that E-mail address is already registered to an account.";
    }
    */

    //this was the last method I tried, and it also never says that the email is in use.
    try{
        $stmt2 = $conn->prepare('SELECT `email` FROM `user` WHERE email = ?');
        $stmt2->bindParam(1, $_POST['email']); 
        $stmt2->execute();
        while($row = $stmt2->fetch(PDO::FETCH_ASSOC)) {
        }
    }
    catch(PDOException $e){
        echo 'ERROR: ' . $e->getMessage();
    }

    if($stmt2->rowCount() > 0){
        //echo "The record exists!";
        $message = "Sorry, that E-mail address is already registered to an account.";
    }

    else{
        // Enter the new user in the database
        $sql = "INSERT INTO users (email, password, firstname, lastname, phone, address, city, zip) VALUES (:email, :password, :firstname, :lastname, :phone, :address, :city, :zip)";
        $stmt = $conn->prepare($sql);

        $stmt->bindParam(':email', $_POST['email']);
        $stmt->bindParam(':password', password_hash($_POST['password'], PASSWORD_BCRYPT));
        $stmt->bindParam(':firstname', $_POST['firstname']);
        $stmt->bindParam(':lastname', $_POST['lastname']);
        $stmt->bindParam(':phone', $_POST['phone']);
        $stmt->bindParam(':address', $_POST['address']);
        $stmt->bindParam(':city', $_POST['city']);
        $stmt->bindParam(':zip', $_POST['zip']);

        if( $stmt->execute() ):
            $message = 'Successfully created new user';
        else:
            $message = 'Sorry there must have been an issue creating your account';
        endif;
    }

endif;

?>

Answer 1

When doing COUNT(*) the server(MySQL) will only allocate memory to store the result of the count and its faster too.

this part of your code that must be corrected:

$records = $conn->prepare('SELECT count(*) FROM users WHERE email = :email');
$records->bindParam(':email', $_POST['email']);
$records->execute();
$results = $records->fetch(PDO::FETCH_NUM);
echo $results[0];