$sth = $dbh->prepare("
                SELECT ip_saddr, ip_daddr, sum( ip_totlen ) AS qwerty
                FROM ulog
                WHERE ip_saddr = '$subnet$start_ip'
                AND date_of_insert
                BETWEEN $date_from
                AND $date_to
                GROUP BY ip_daddr
                ORDER BY qwerty DESC
                ");
        $sth->execute;

        while ( @row = $sth->fetchrow_array ) {
                   $sth = $dbh->prepare( q{
                           INSERT INTO simple (ip_saddr, ip_daddr, ip_totlen) values (?,?,?)
                           }) || die "Can't prepare statement: $DBI::errstr";
                   $sth->execute($row[ 0 ], $row[ 1 ], $row[ 1 ]);
        }

INSERT INTO simple( ip_saddr, ip_daddr, ip_totlen ) 
SELECT ip_saddr, ip_daddr, sum( ip_totlen ) AS qwerty
FROM ulog
WHERE ip_saddr = '172.16.16.1'
AND date_of_insert
BETWEEN  050516000000  
AND  050917000000  
GROUP BY ip_daddr
ORDER BY qwerty DESC