The number of rows returned is the number actually fetched, not the number potentially available. If one limits the number of rows to fetch, the number of rows returned will be bound by that limit. For example...
$nrows = oci_fetch_all($statement, $results, 0, 1);
would result in a returned value of '0' if there are no rows found for the statement, or '1' if any rows were found, regardless of the number actually present in the database.