Question

我有一张表，消息在发生时存储。通常会有一条消息＆＃39; A＆＃39;有时候A会被一条消息“B＆B”分开。现在我想对这些值进行分组，以便我能够对它们进行分析，例如找到最长的A＆＃39; -streak或分发A＆＃39; -streaks。

我已经尝试过COUNT-OVER查询，但是会继续计算每条消息。

SELECT message, COUNT(*) OVER (ORDER BY Timestamp RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW)

这是我的示例数据：

Timestamp        Message
20150329 00:00   A
20150329 00:01   A
20150329 00:02   B
20150329 00:03   A
20150329 00:04   A
20150329 00:05   A
20150329 00:06   B

我想要关注输出

Message    COUNT
A          2
B          1
A          3
B          1

Answer 1

这很有趣：）

;WITH cte as (
SELECT Messages.Message, Timestamp, 
ROW_NUMBER() OVER(PARTITION BY Message ORDER BY Timestamp) AS gn,
ROW_NUMBER() OVER (ORDER BY Timestamp) AS rn
FROM Messages
), cte2 AS (
SELECT Message, Timestamp, gn, rn, gn - rn  as gb
FROM cte 
), cte3 AS (
SELECT Message, MIN(Timestamp) As Ts, COUNT(1) as Cnt
FROM cte2
GROUP BY Message, gb)
SELECT Message, Cnt FROM cte3
ORDER BY Ts

以下是结果集：

  Message   Cnt
    A   2
    B   1
    A   3
    B   1

查询可能会更短，但我会以这种方式发布，这样您就可以看到发生了什么。结果完全按照要求。这是最重要的部分gn - rn，我们的想法是对每个分区中的行进行编号，同时对整个集合中的行进行编号，然后如果从另一个中减去这一行，您将获得＆。＃39;秩＆＃39;每个小组。

;WITH cte as (
SELECT Messages.Message, Timestamp, 
ROW_NUMBER() OVER(PARTITION BY Message ORDER BY Timestamp) AS gn,
ROW_NUMBER() OVER (ORDER BY Timestamp) AS rn
FROM Messages
), cte2 AS (
SELECT Message, Timestamp, gn, rn, gn - rn  as gb
FROM cte 
)
SELECT * FROM cte2

Message Timestamp           gn  rn  gb
A   2015-03-29 00:00:00.000 1   1   0
A   2015-03-29 00:01:00.000 2   2   0
B   2015-03-29 00:02:00.000 1   3   -2
A   2015-03-29 00:03:00.000 3   4   -1
A   2015-03-29 00:04:00.000 4   5   -1
A   2015-03-29 00:05:00.000 5   6   -1
B   2015-03-29 00:06:00.000 2   7   -5

Answer 2

这是一个小小的解决方案：

DECLARE @t TABLE ( d DATE, m CHAR(1) )

INSERT  INTO @t
VALUES  ( '20150301', 'A' ),
        ( '20150302', 'A' ),
        ( '20150303', 'B' ),
        ( '20150304', 'A' ),
        ( '20150305', 'A' ),
        ( '20150306', 'A' ),
        ( '20150307', 'B' );

WITH 
c1 AS(SELECT d, m, IIF(LAG(m, 1, m) OVER(ORDER BY d) = m, 0, 1) AS n FROM @t),
c2 AS(SELECT m, SUM(n) OVER(ORDER BY d) AS n FROM c1) 
    SELECT m, COUNT(*) AS c
    FROM c2
    GROUP BY m, n

输出：

m   c
A   2
B   1
A   3
B   1

我们的想法是在消息发生变化的行中获取值1：

2015-03-01  A   0
2015-03-02  A   0
2015-03-03  B   1
2015-03-04  A   1
2015-03-05  A   0
2015-03-06  A   0
2015-03-07  B   1

第二步是当前行值+所有先前值的总和：

2015-03-01  A   0
2015-03-02  A   0
2015-03-03  B   1
2015-03-04  A   2
2015-03-05  A   2
2015-03-06  A   2
2015-03-07  B   3

通过这种方式，您可以按消息列和计算列获取分组集。

按值对行进行分组和计数，直到更改为止

2 个答案: