Selecting data from multiple rows into a single row
Join the table to itself.

So:

select yt1.demand_id, yt1.debit_status, yt2.customer
from yourtable yt1, yourtable yt2
where yt1.demand_id = yt2.demand_id
and yt1.debit_status is not null
and yt2.customer is not null;


Or (if batch_number can reliably be used to fetch the 2 rows needed to make a single row:

select yt1.demand_id, yt1.debit_status, yt2.customer
from yourtable yt1, yourtable yt2
where yt1.demand_id = yt2.demand_id
and yt1.batch_number = 1
and yt2.batch_number = 2;


SQL fiddle.