column|order_id|not_nullable|number(12)
column|order_date|not_nullable|timestamp(6)
column|order_mode|nullable|varchar2(8)
column|customer_id|not_nullable|number(6)
column|order_status|nullable|number(2)
column|order_total|nullable|number(8,2)
column|sales_rep_id|nullable|number(6)
column|promotion_id|nullable|number(6)
check|(order_mode in ('direct','online')) 
check|(order_total >= 0) 
pkey|order_id
fkey|sales_rep_id|hr.employees.employee_id
fkey|customer_id|oe.customers.customer_id