should be
if ($insert_stmt = $mysqli->prepare("INSERT INTO members (username, email, password, salt, privilegio) VALUES (?,?,?,?,?)") {
$insert_stmt->bind_param('sssss', $username, $email, $password, $random_salt, $privilegio);
// Execute the prepared query.
$insert_stmt->execute();
}
solved Warning: mysqli_stmt::bind_param() [mysqli-stmt.bind-param]: Number of variables doesn’t match number of parameters in prepare [closed]