这是我的表格(仅包括相关列)
Table: carts
address_id - integer
Table: addresses
name - varchar
phone - varchar
Table: orders
order_number - integer (this is the foreign key for cart table)
我想获取只订购过一次的客户的电话号码,因此我构造了以下查询
select addresses.phone
from orders
inner join carts on orders.order_number = carts.id
inner join address on carts.address_id = addresses.id
group by addresses.phone
having count(orders.*) = 1;
这很好用!但我确实还需要选择客户名称和订单号,我将选择语句更新为
select addresses.phone, addresses.name, orders.order_number ...
现在,postgres 敦促我将这些列包含在 GROUP BY
子句中,但这不会返回我想要的结果。
我尝试使用如下子查询,这似乎得到了我想要的结果
select addresses.phone, (select ad.name from addresses ad where ad.phone = addresses.phone) ...
但是使用子查询是解决这个问题的唯一方法吗?或者有没有更简单/最佳的方法?
最佳答案
您可以通过 window function 来实现此目的这不需要将所有内容分组:
select *
from (
select addresses.phone, addresses.name, orders.order_number,
count(orders.order_number) over (partition by addresses.phone) as cnt
from orders
inner join carts on orders.order_number = carts.id
inner join address on carts.address_id = addresses.id
) t
where cnt = 1;
关于sql - 请勿在分组依据中包含选择列,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/30932989/