sub get_table_CRC {

    my $dbh = shift;
    my $tablename = shift;

    my $fields = get_fields($dbh, $tablename);

    my $check_table = qq[
    SELECT 
        COUNT(*) AS cnt, 
        CONCAT(SUM(CONV(
            SUBSTRING(\@CRC:=MD5(
                CONCAT_WS('/##/',$fields)),1,8),16,10 )), 
        SUM(CONV(SUBSTRING(\@CRC, 9,8),16,10)),
        SUM(CONV(SUBSTRING(\@CRC,17,8),16,10)),
        SUM(CONV(SUBSTRING(\@CRC,25,8),16,10))
        ) AS sig 
    FROM 
        $tablename 
    ];

    # uncomment the following line to see the full query
    # print $check_table,$/;

    my ($count, $crc);
    eval { ($count, $crc) = $dbh->selectrow_array($check_table)};
    if ($@) 
    {
         return undef;
    }
    return [$count, $crc];
}