sub _get_users {
    my $self = shift;
    my $sql  = "select * from my_table order by username";
    $self->dbh->{PrintError} = 0;
    $self->dbh->{RaiseError} = 1;
    # fetchrow_hashref?
    my $sth = $self->dbh->prepare($sql);
    $sth->execute();
    my $rs = $sth->fetchall_arrayref(
        {
            user_id    => 1,
            username   => 1,
            first_name => 1,
            last_name  => 1
        }
    );
    return $rs;
}