Monday 3 September 2018

PHP connect_error does not return anything, but the code does not work

It always returns empty connect_error value. It connects to mySQL properly. I want to create simple registering system on my page. I'm new to PHP and HTML, so I don't know what is wrong in this code. MySQL works properly, I think, so maybe something is wrong with my SQL code?

This is my PHP code:
<?php
$link = @new mysqli('valid localhost', 'valid user', 'valid password', 'valid database');
if ($link->connect_error!=0) {
    die('Could not connect: ' . $link->connect_error);
}

$login = $_POST['login'];
$password = $_POST['password'];
$confirm = $_POST['confirmpassword'];
$email = $_POST['email'];

$result = mysql_query($sql, "SELECT COUNT(*) AS num_rows FROM `users` WHERE username='{$login}' LIMIT 1;");
$row = mysql_fetch_array($sql, $result);
if($row["num_rows"] < 0){
    header('Location: index.php');
    return;
}

if($password != $confirm) {
    header('Location: index.php');
    return;
}

$login = htmlentities($login, ENT_QUOTES, "UTF-8");
$password = htmlentities($password, ENT_QUOTES, "UTF-8");
$email = htmlentities($email, ENT_QUOTES, "UTF-8");

$sql = sprintf("INSERT INTO `users` (`username`, `password`, `email`) VALUES
('%s', '%s', '%s');",
mysqli_real_escape_string($link, $login),
mysqli_real_escape_string($link, $password),
mysqli_real_escape_string($link, $email));
if (mysql_query($sql, $link)) {
    echo "User created successfully!\n";
} else {
    echo 'Error creating user: ' . $link->connect_error . "\n";
}
?>
HTML code:
<!DOCTYPE HTML>
<html lang="en">
<head>
    <meta charset="utf-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1" />
    <title>Awesome title</title>
</head>

<body>

    Register<br /><br />

    <form action="register.php" method="post">

        Login: <br /> <input type="text" name="login" /> <br />
        Email: <br /> <input type="email" name="email" /> <br />
        Password: <br /> <input type="password" name="password" /> <br />
        Confirm password: <br /> <input type="password" name="confirmpassword" /> <br /><br />
        <input type="submit" value="Register" />

    </form>
</body>
</html>
and MySQL table:
CREATE TABLE IF NOT EXISTS `users` (
  `username` text collate utf8_polish_ci NOT NULL,
  `password` text collate utf8_polish_ci NOT NULL,
  `email` text collate utf8_polish_ci NOT NULL
) ENGINE=MyISAM  DEFAULT CHARSET=utf8 COLLATE=utf8_polish_ci;
This is what I get:
Error creating user:
Change
echo 'Error creating user: ' . $link->connect_error . "\n";
to
echo 'Error creating user: ' . $link->error . "\n";
Also, you're mixing mysql and mysqli, and mixing object oriented with procedural.
Try this:
<?php
$link = @new mysqli('valid localhost', 'valid user', 'valid password', 'valid database');
if ($link->connect_error) {
    die('Could not connect: ' . $link->connect_error);
}

$login = $_POST['login'];
$password = $_POST['password'];
$confirm = $_POST['confirmpassword'];
$email = $_POST['email'];

$result = $link->query("SELECT COUNT(*) AS num_rows FROM `users` WHERE username='{$login}' LIMIT 1;");
$row = $result->fetch();
if($result->num_rows < 0){
    header('Location: index.php');
    return;
}

if($password != $confirm) {
    header('Location: index.php');
    return;
}

$login = htmlentities($login, ENT_QUOTES, "UTF-8");
$password = htmlentities($password, ENT_QUOTES, "UTF-8");
$email = htmlentities($email, ENT_QUOTES, "UTF-8");

$sql = sprintf("INSERT INTO `users` (`username`, `password`, `email`) VALUES
('%s', '%s', '%s');",
$link->real_escape_string($login),
$link->real_escape_string($password),
$link->real_escape_string($email));
if ($link->query($sql)) {
    echo "User created successfully!\n";
} else {
    echo 'Error creating user: ' . $result->error . "\n";
}
?>

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