特定产品的mysql订单

Question

I have 3 tables orders, orders_products, and products. I have joined them to get products for each order..

SELECT o.orders_id, p.products_id, p.item_type 
from orders o 
join orders_products op on o.orders_id = op.orders_id 
join products p on op.products_id = p.products_id

Now I want to only get the orders that only have p.item_type = 1 or p.item_type = 2. (if an order has products of type 1, 2, and 3, don't show, only orders with product types 1 or 2)

Answer 1

If you want only the orders, you can use group by and having . The following gets orders with items 1 and 2 and none others:

select op.orders_id
from orders_products op join
     products p
     on op.products_id = p.products_id
group by op.orders_id
having sum(p.item_type = 1) > 0 and
       sum(p.item_type = 2) > 0 and
       sum(p.item_type not in (1, 2)) = 0;

Note that the orders table is not needed.

You can use this having clause for 1 or 2 and no others:

having sum(p.item_type in (1, 2) > 0 and
       sum(p.item_type not in (1, 2)) = 0;