my $sql = <<SQLCODE;
  SELECT
    a.ip
  FROM
    ALLIP a,
    USER u
  WHERE
    a.user_id = u.id AND
    u.id = ?
  GROUP BY
    a.ip
SQLCODE

my $sth = $dbh->prepare( $sql );
if ( $sth && $sth->execute( $user_id ) )
{
    while ( my $row = $sth->fetchrow_arrayref() )
    {
        print( "IP address " . $row->[0] . "\n" );
    }
    $sth->finish();
}
else
{
    die( "Database error " . $dbh->errstr . "\n" );
}