...b.customer_id,
b.c12_gross_amt
from customer_computed_value b, sample_custs c
where b.customer_id = c.customer_id
union
select x.*
from
(
select 'Order Basket',
e.customer_id,
sum(d.total_gross_amt)
from order_basket d, sample_custs e
where d.customer_id =...