Mysql 尝试获取最新记录时在on子句中获取未知列

我有两个表orders和order_项我试图使用内部联接获取每天的最后一个order_和，但在第二个联接中遇到错误

on子句中的未知列“o.last\u order\u date”

这是我的问题

select 
    date(o.created_at) date_of_month,
    sum(o.order_sum) as total_order_sum,
    sum(i.total_energy_used) as total_energy_used,
    max(o.created_at) as last_order_date,
    o2.order_sum as last_order_sum
from orders o
inner join (
    select order_id, sum(energy_used) total_energy_used
    from order_items i
    group by order_id
) i on o.id = i.order_id
inner join (
  select created_at, order_sum from orders
) o2 on o2.created_at = o.last_order_date
group by date(o.created_at)

这是我想要得到的结果

+---------------+-----------------+-------------------+---------------------+----------------+
| date_of_month | total_order_sum | total_energy_used | last_order_date     | last_order_sum |
+---------------+-----------------+-------------------+---------------------+----------------+
| 2020-01-25    | 35.13           | 164               | 2020-01-25 15:23:00 | 10.00          |
| 2020-01-26    | 64.00           | 1                 | 2020-01-26 19:14:00 | 50.00          |
| 2020-01-27    | 35.00           | 5                 | 2020-01-27 11:13:00 | 35.00          |
+---------------+-----------------+-------------------+---------------------+----------------+

这里是对模式的修改

---

聚合列尚不能在联接条件中使用。 您可以尝试使用子选择来执行此操作

select t.* 
,o2.order_sum as last_order_sum
from (
    select 
        date(o.created_at) date_of_month,
        sum(o.order_sum) as total_order_sum,
        sum(i.total_energy_used) as total_energy_used,
        max(o.created_at) as last_order_date

    from orders o
    inner join (
        select order_id, sum(energy_used) total_energy_used
        from order_items i
        group by order_id
    ) i on o.id = i.order_id
     group by date(o.created_at) 
) t
inner join (
  select created_at, order_sum from orders
) o2 on o2.created_at =t.last_order_date

---

结果：

您在上一个问题中已经问过这个问题，第二个内部连接就快到了

select 
    date(o.created_at) date_of_month,
    sum(order_sum) as total_order_sum,
    sum(i.total_energy_used) total_energy_used,
    max(o.created_at) lastorderdate,
    max(s.last_order_sum) last_order_sum
from orders o
inner join (
    select order_id, sum(energy_used) total_energy_used
    from order_items i
    group by order_id
) i on o.id = i.order_id
join
(select order_sum last_order_sum,created_at
    from orders o
    where created_at = (select max(created_at) from orders o1 where date(o1.created_at) = date(o.created_at))
) s on date(s.created_at) = date(o.created_at) 
group by date(o.created_at);

---

您可以在此处使用相关子查询：

select date(o.created_at) date_of_month,
       sum(o.order_sum) as total_order_sum,
       sum(i.total_energy_used) as total_energy_used,
       max(o.created_at) as last_order_date,
       (select o1.order_sum 
        from orders o1 where date(o.created_at) = date(o1.created_at)
        order by o1.created_at desc
        limit 1
       ) as last_order_sum    
from orders o inner join 
     (select order_id, sum(energy_used) total_energy_used
      from order_items i
      group by order_id
     ) i 
     on o.id = i.order_id
group by date(o.created_at);

---

这里是演示

我有点困惑；我觉得我们已经讨论过了，但是你提供了一个fiddle@Strawberry我在学习。除了每天最后一笔订单，我们什么都拿到了。由于某种原因，我仍然无法获取…orders表是否有last_order_date列？@jarlh不，正如您在小提琴中看到的，last_order_date是从内部join派生的列。这些仅在ORDER BY条款中可用。