返回内部联接表中的最大日期

Question

我有一个订单和order_items表：

Order
-id

Items
-id
-order_id
-date_added
-price

除了以下内容之外，我还想将MAX date_added值作为item的列返回。我怎么能这样做？

select item.id, count(*)
from orders o
    inner join items i on o.id = i.order_id
group by item.id
order by count(*) desc

Answer 1

只需使用MAX功能

即可

select item.id, count(*), MAX(date_added)
from orders o
    inner join items i on o.id = i.order_id
group by item.id
order by count(*) desc

Answer 2

这个简单的查询应该为你做到：

select item.id, count(*) count_of_orders, max(date_added ) max_date_added
from orders o
    inner join items i on o.id = i.order_id
group by item.id
order by count(*) desc