mysql - 天数累计

Question

我有一个如下的 MySQL 表：

date         count
2010-01-01   5
2010-01-02   6
2010-01-03   7

如何将每天的总和累积到下一天？所以结果是这样的：

date         acum per day
2010-01-01   5
2010-01-02   11
2010-01-03   18

我想我需要某种for（每个日期）......但没有线索。

---

只是我在 Eric 的回答之后使用的最后一个查询。（谢谢）。

选择 t1.dia, sum(t2.operacions), sum(t2.amount) FROM

(SELECT count(*) operations, sum(amount), date(b.timestamp) dia
    FROM transactions b group by date(b.timestamp)) t1 

INNER JOIN 

(SELECT count(*) operations, sum(amount), date(b.timestamp) dia
    FROM transactions b group by date(b.timestamp)) t2 

ON t2.dia <= t1.dia GROUP BY t1.dia

Answer 1

好吧，我认为这会起作用，但不确定性能如何：

SELECT t1.date, sum(t2.count)
FROM mytable t1 INNER JOIN mytable t2 ON t2.date <= t1.date
GROUP BY t1.date

Answer 2

无需加入即可解决此问题。

SET @cumulative_sum := 0;
SELECT date, @cumulative_sum := @cumulative_sum + count AS cumulative_sum
FROM table
ORDER BY date ASC

Answer 3

使用 <= 进行自连接并对行求和即可完成此操作。