access variable from different method within same model class

[eluser]ranjitbd[/eluser]
// this is a model class
class Holiday_model extends Model
{
function Holiday_model()
{
parent::Model();
$this->load->database('holiday', TRUE);
}

function view_package()
{
$sql = "select * from package_details";
// i want to use this $sql in the method get_package_details()mentioned below

$query = $this->db->query($sql);
return $query->result_array();
}

function get_package_details($id)
{
// here how can i access the $sql from view_package() method mentioned above.and set it within $new_sql

$new_sql = ;//please write here the code

$row = $new_sql." where id = '$id'";

$query = $this->db->query($row);
return $query->row_array();
}

}
?>