Sql 使用以前的数据分组

有一个用户表

ID | DATE_CR

按月分组

SELECT TO_CHAR (operation_time, 'YYYY-MM'), count(ID) from users GROUP BY TO_CHAR (operation_time, 'YYYY-MM')

我登记了月数

January 10
February 3
March 5

但在输出端，我想得到

January 10
February 13
March 18

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一种方法是将当前查询放入CTE中，然后使用相关子查询来计算运行总数

WITH cte AS (
    SELECT
        TO_CHAR (operation_time, 'YYYY-MM') AS mdate,
        COUNT(ID) AS total
    FROM users
    GROUP BY TO_CHAR (operation_time, 'YYYY-MM')
)
SELECT t1.mdate,
       (SELECT SUM(t2.total) FROM cte t2
        WHERE t2.mdate <= t1.mdate) AS running_total
FROM cte t1

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另一种可能性能更好的方法是使用窗口函数。像@GordonLinoff这样的人会告诉你的。

这不是一个窗口功能吗？