my $conn = DBI->connect("dbi...);

sub {
 my $conn = shift;
 ...
}

##</code><code>##

use somepackage;

my $conn = somepackage::connectdb();

$conn->{AutoCommit} = 0;

...

sub foo {
  my ($conn, $bar) = @_;
  my $sth = $conn->prepare(qq{
    SELECT COUNT(*) AS MYCOUNT FROM MYTABLE WHERE ID=?
  });
  $sth->execute($bar);
  my $ref = $sth->fetchrow_hashref();
  $sth->finish();
  return $ref->{MYCOUNT};
}

print &foo($conn, 'some id');

...

$conn->disconnect();

__END__


##</code><code>##

sub connectdb {
	my $user       = 'user';
  my $password   = 'password';
	my $host       = 'host';
	my $sid        = 'SID';
	return (DBI->connect("dbi:Oracle:host=$host;sid=$sid", $user, $password,
		{PrintError => 1, RaiseError => 1, AutoCommit => 0}));
}