How can one efficiently check for the uniqueness of both username and email in a registration form using PHP?

To efficiently check for the uniqueness of both username and email in a registration form using PHP, you can query the database to see if the username or email already exists before allowing the user to submit the form. This can be done by running SELECT queries on the database to check if the username or email already exists in the database. If a matching record is found, display an error message to the user indicating that the username or email is already in use. 

// Check if username or email already exists in the database
$username = $_POST['username'];
$email = $_POST['email'];

// Connect to the database
$conn = new mysqli($servername, $username, $password, $dbname);

// Check if username already exists
$username_check = $conn->query("SELECT * FROM users WHERE username = '$username'");

if ($username_check->num_rows > 0) {
    echo "Username already exists. Please choose a different username.";
}

// Check if email already exists
$email_check = $conn->query("SELECT * FROM users WHERE email = '$email'");

if ($email_check->num_rows > 0) {
    echo "Email already exists. Please use a different email address.";
}

// If both username and email are unique, proceed with registration
// Insert user data into the database

Keywords

PHP registration form uniqueness check username email

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