Show me the order with invoice number 10.
select * from orders as t1 join shipments as t2 on t1.order_id = t2.order_id where invoice_number = 10
When was that order placed? Give me the date.
select t1.date_order_placed from orders as t1 join shipments as t2 on t1.order_id = t2.order_id where t2.invoice_number = 10