select sales_flat_order.entity_id
from sales_flat_order
where not exists (
select 1
from download_tracknumber
where download_tracknumber.id = sales_flat_order.entity_id
)
select sales_flat_order.entity_id
from sales_flat_order
where not exists (
select 1
from download_tracknumber
where download_tracknumber.id = sales_flat_order.entity_id
)