Question

情况：

我有一个表，其中包含付费和免费交易，余额表将免费和付费交易合并在一起。

目标：

我需要获取已支付的交易总额和最近的余额

结构：

+-----------+---------+--------+-------------+------------+
| member_id | balance | amount |    type     | issue_date |
+-----------+---------+--------+-------------+------------+
| varchar   | int     | int    | pay or free | datetime   |
+-----------+---------+--------+-------------+------------+

当前查询：

        select t1.member_id, t2.balance, sum(t1.amount) as total
        from table AS t1
        inner join (select member_id, 
                            balance, 
                            ROW_NUMBER() over (partition by member_id order by issue_date desc) AS ranks 
                    from table
                    ) AS t2 on t1.member_id=t2.member_id and t2.ranks = 1
        where [type] = 'pay'
        group by t1.member_id, t2.balance

这似乎可行，但对于没有索引issue_date的数百万行的表而言，效率极低。

有什么建议吗？

Answer 1

一种方法使用窗口函数和select distinct：

select distinct t.member_id,
       first_value(case when t.type = 'pay' then t.balance end) over (partition by t.member_id order by (case when t.type = 'pay' then 1 else 2 end), t.issue_date desc), 
       sum(t.amount) over (partition by t.member_id) as total
from table t;

不幸的是，SQL没有first_value()聚合函数。

根据另一列获取最新值，并独立求和另一列

1 个答案: