CREATE PROCEDURE dbo.Foo (
  @Required Int,
  @Optional Int = 0
) AS ...

##</code><code>##

my $sth2 = $db->prepare('EXEC dbo.Foo ?, ?');
$sth2->execute(1,2);

##</code><code>##

my $sth1 = $db->prepare('EXEC dbo.Foo ?');
$sth1->execute(1); # use the default for the second param