simpe, but basic active record question

so, if there is no other method, i think i'll just use plain old mysql
I was convinced rails had a better method...

If you need the lines for for a given order, why not just do something like this:

@order = @customer.orders.find(order_id, :include => :order_lines)

That'll use 1 query - the lines for that order will be accessible via @order.order_lines.