select avg(a.items) items_per_order from (select order_id, count(*) items from order_items group by order_id) a

select avg(a.orders) items_per_customer from (select customer_id, count(*) orders from orders group by customer_id ) a

select distinct order_status from orders

select count(*) from ( select order_id, customer_id, order_status, order_date, required_date, shipped_date, store_id, staff_id from orders where order_id in (?)) a

select c.customer_id, c.first_name, c.last_name, o.order_status from customers c, orders o where c.customer_id = o.customer_id and o.order_status = ?

select count(*) from order_items