SQL Delete row if no relationships present

Question

I have a Purchase Order table and an items table, a Purchase Order can have many Items but I want to remove all those purchase orders that have no items. Is that possible in SQL?

Answer 1

Of course.

delete from purchase_orders
    where not exists (select 1
                      from purchase_order_items poi
                      where poi.purchase_order_id = purcahse_orders.purchase_order_id
                     );