When was the oldest order placed?
select date_order_placed from orders order by date_order_placed limit 1
What's the id of the customer who placed it?
select customer_id from orders order by date_order_placed limit 1
What's the id of the order?
select order_id from orders order by date_order_placed limit 1
Show me both id's.
select order_id, customer_id from orders order by date_order_placed limit 1