have a feeling that you're not modifying the %ENV that you think you are - i.e., it is not in the proper scope and you may be modifying the hash in a disjoint scope.

What other %ENV is there in Perl?

What other %ENV is there in Perl?

You could make a lexical named %ENV, and it would mask %main::ENV. That doesn't appear to be the case here, but that's another one.

below is my code 

#!/usr/bin/perl


use DBI;

$ENV{'LD_LIBRARY_PATH'}= "/opt/instantclient_10_2/";
$ENV{'ORACLE_HOME'}= "/opt/instantclient_10_2/";


$database = "idm";
$username = "idm";
$password = "idm";
$hostname = "host";

$output = &connectCBMS(900010);
print $output;

sub connectCBMS {
print "Connecting to Database for user $staffcode";
$db = DBI->connect("DBI:Oracle:host=$hostname;sid=$database",$username,$password);
unless($db) {
    print "(ERROR) Failed to connect to $hostname.";
    return;
  }

my ($staffcode) = @_;
# Execute a Query
my $sql = qq{ SELECT REGISTRATIONDAY FROM CBMS WHERE STAFFCODE = ? };
my $sth = $db->prepare( $sql );

print $staffcode;
$sth->bind_param( 1, $staffcode );
$sth->execute();

while ( $row = $sth->fetchrow_array()) {
   if (!$row) {

              return;

             }
        else {

          return ($row);
              }
}

$sth->finish();
$db->disconnect();
return;
}