Question

Function

  public function isUsernameAvailable($username) {
        $sql = "SELECT COUNT(*) FROM users WHERE username = '$username'";
        $sql = $this->db->quote($sql);

        if ($sth = $this->db->query($sql)) {
            if ($sth->fetchColumn() > 0) {
                return false;
            } else {
                return true;
            }
        }
    }


if (!$user->isUsernameAvailable($_POST['username'])) {
        echo 'The username is already taken!';
        $error = 1;
    }

I get the output “The username is already taken!” even though It isn’t.

Answer 1

select count(*)... will ALWAYS return a record, even nothing is matched

so, you can try this :

select 1 from ...;

between, a proper method to check any record return should be using rowCount

as indicate by the rest :-

1. you should make use of bind rather than using quote
2. function should always return a value