MySQL中更复杂的累积和列 [英] More complex cumulative sum column in mysql

问题描述

我阅读了在MySQL中创建累积总和列，然后试图使其适应我的工作，但我似乎无法正确地做到这一点.

I read Create a Cumulative Sum Column in MySQL, and tried to adapt it to what I'm doing, but I can't seem to get it right.

表格:

Id (primary key)
AcctId
CommodId
Date
PnL

有一个唯一索引，其中包含AcctId，CommodId，Date.我想获得按日期分组的累计总数.

There is a unique index which contains AcctId, CommodId, Date. I want to get a cumulative total grouped by date.

此查询

select c.date
   , c.pnl
   ,(@cum := @cum + c.pnl) as "cum_pnl"
   from commoddata c join (select @cum := 0) r
   where
   c.acctid = 2
   and
   c.date >= "2011-01-01"
   and
   c.date <= "2011-01-31"
   order by c.date

将正确计算所有记录的运行总计，以格式显示数据

will correctly calculate the running total for all records, showing data in the format

date        pnl       cum_pnl
========    ======    =======
2011-01-01       1          1
2011-01-01       1          2
2011-01-01       1          3
2011-01-01       1          4
2011-01-02       1          5
2011-01-02       1          6
...

(每个日期可能有很多记录).我想要的是

(there can be many records per date). What I want is

date        cum_pnl
========    =======
2011-01-01       4
2011-01-02       6
...

但是我没有尝试过. TIA.

But nothing I've tried works. TIA.

推荐答案

或者，我认为您可以将所有pnl替换为sum(pnl)，并让您的@cum在其中运行.我认为它看起来像这样:

Alternately I think you can replace all your pnl with sum(pnl), and let your @cum run across those. I think it would look like this:

select c.date
   ,SUM(c.pnl)
   ,(@cum := @cum + SUM(c.pnl)) as "cum_pnl"
   from commoddata c join (select @cum := 0) r
   where
   c.acctid = 2 and c.date >= "2011-01-01" and c.date <= "2011-01-31"
   order by c.date
   GROUP BY c.date

我只是想弄清楚，如果cum_pnl不是按表达式分组时，SQL是否会让您为选择cum_pnl感到烦恼...也许您也可以尝试按它分组?

I'm just trying to figure out if SQL will give you grief over selecting cum_pnl when it is not a group by expression... maybe you can try grouping by it as well?

编辑新思路，如果您真的不喜欢嵌套查询，请用汇总的分组查询替换commoddata

EDIT New Idea, if you're really not averse to nested queries, replace commoddata with a summed grouped query

select c.date
   ,c.pnl
   ,(@cum := @cum + c.pnl) as "cum_pnl"
   from 
       (SELECT date, sum(pnl) as pnl FROM commoddata WHERE [conditions] GROUP BY date) c 
       join (select @cum := 0) r
   order by c.date

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