sql - 如何使用 SUM 在 sql select 中获取表中每一行的最后 15 分钟值（会话）

Question

我想要一张桌子

1> requestTime 2> NumberOfSessionsInLast15minutes

如何编写查询以获取 requestTime 列相同且 NumberOfSessions 列将是过去 15 分钟的会话总和的表

例子：

这个 2012-06-06 00:12:00.0000 的会话数应该是 2012-06-06 00:12:00.0000 和 (2012-06-06 00:12:00.0000) - 15 分钟之间的会话总和。

Answer 1

您可以使用子查询来检索会话数：

select  s1.requesttime
,       (
        select  sum(NumberOfSessions)
        from    sessions s2
        where   dateadd(minute, -15, s1.requesttime) < s2.requesttime
                and s2.requesttime <= s1.requesttime
        ) as TotalNumberOfSessions
from    sessions s1

Answer 2

DECLARE
  @reportTime   DATETIME
SELECT
  @reportTime = '2012-06-06 00:12'

SELECT
  @reportTime,
  SUM(NumberOfSessions)
FROM
  yourTable
WHERE
      requestTime >  DATEADD(minute, -15, @reportTime)
  AND requestTime <= @reportTime

根据您的需要和数据的确切行为混合和匹配>=、>和。<<=

（通常 15 分钟的窗口是>= 00:00 AND < 00:15，但您的定义与此略有不同。）

如果您希望源表中的所有记录都使用它...

SELECT
  base.requestTime,
  SUM(history.NumberOfSessions)
FROM
  yourTable    AS base
INNER JOIN
  yourTable    AS history
    ON  history.requestTime >  DATEADD(minute, -15, base.requestTime)
    AND history.requestTime <= base.requestTime
GROUP BY
  base.requestTime

Answer 3

这是一种通用的方法，提供给定日期的 15 分钟时间段的细分：

DECLARE @requests TABLE(requestTime DATETIME, NumberOfSessions INT);

INSERT @requests SELECT '20120605 23:59', 2
UNION ALL SELECT '20120606 00:00', 500
UNION ALL SELECT '20120606 00:07', 400
UNION ALL SELECT '20120606 00:17', 300
UNION ALL SELECT '20120606 23:57', 500
UNION ALL SELECT '20120607 00:00', 100;

DECLARE @day SMALLDATETIME; -- this would be a stored procedure parameter
SET @day = '20120606';

;WITH n AS 
(
  SELECT TOP 96 n = DATEADD(MINUTE, 15*
  (ROW_NUMBER() OVER (ORDER BY [object_id])-1), @day)
  FROM sys.all_columns ORDER BY [object_id]
)
SELECT requestTime = n.n, SumNumberOfSessions = COALESCE(SUM(NumberOfSessions), 0)
FROM n LEFT OUTER JOIN @requests AS r
ON r.requestTime >= n
AND r.requestTime < DATEADD(MINUTE, 15, n)
GROUP BY n.n
ORDER BY requestTime;

结果：

requestTime                SumNumberOfSessions
-----------------------    -------------------
2012-06-06 00:00:00.000    900
2012-06-06 00:15:00.000    300
2012-06-06 00:30:00.000    0
...
2012-06-06 23:30:00.000    0
2012-06-06 23:45:00.000    500