Does it work from the command line?

First glance says you don't need to the line "use DBD::Oracle;", just DBI. You load the DBI later. For example:

use strict;
use DBI;

my $dbname = 'ORCL'; #name of database
# Here is where DBI loads DBD::Oracle
my $dbh = DBI->connect( "dbi:Oracle:$dbname",
                        'scott',
                        'tiger',
                       ) || die "Database connection not made: $DBI::e
+rrstr";
$dbh->disconnect;
[download]

HTH

Update: You should probably search the mod_perl site for "persistent database connections"

Clarified comment about "use DBI::Oracle;"