Selecting tiny numbers with many significant digits returns NULL

  While trying to run a statistical calculation Perl script that I have 
been running for several years it started crashing. I spent some time to 
track down the problem to my Perl script selecting a fairly small value 
from a table and getting NULL in response. I wrote a simplified script 
that demonstrated the problem so I could experiment to see what was 
going on. Below is that script:

use DBI;
use English;
use strict;
no strict 'subs';

my ($dbh, $sth, $foobar);

$dbh = DBI->connect('DBI:ODBC:<database_name>', '', '', {RaiseError =>  1, AutoCommit =>  1});

$sth = $dbh->prepare("select 2.775557561562E-17");
$sth->execute();
$foobar = $sth->fetchrow;
print "foobar=$foobar\n";

$sth = $dbh->prepare("select 2.7755575615629E-17");
$sth->execute();
$foobar = $sth->fetchrow;
print "foobar=$foobar\n";

exit(0);


When I run this program the output is as follows:

foobar=2.775557561562E-17
foobar=


It seems that when the mantissa of a number has too many significant 
digits DBI returns a NULL instead of the number. The only difference in 
the second case is the addition of an additional digit. This took some 
time to boil my problem down to this simple issue. Searching on the 
Internet has yet to yield any similar issues (with or without 
solutions). As a result I am appealing to this list to either point out 
something incredibly bone-headed that I am doing or to try to reproduce 
this in their environment and propose a solution.

Right now I am looking at dropping in a bunch of ROUND() functions in my 
SQL that is generating the number giving me fits but that seems to be 
more of a kludge workaround than a proper fix. Any thoughts from the 
deities on this list?

Before anybody asks, I'm running Perl v5.10.1 (with all the most recent 
module versions loaded through ppm) on a Windows 7 machine.

Thanks in advance for anybody spending time on this issue that is 
keeping me from doing useful work.



KM