记录结果的连续计数

Question

我正在研究一个数据结构，其中包含每个人的正面或负面结果列表。

示例数据（id是一个身份）：

id      person  result
1       1       0
2       1       1
3       1       1
4       2       1
5       2       0
6       1       1
7       1       0
8       2       0
9       2       0
10      2       0

有了这个我想计算每个人的最大consecutive result = 1个数。此示例中的结果将是

person  max_count
1       3
2       1

我试过这样使用 ROW_NUMBER() OVER (PARTITION BY)

SELECT person, 
ROW_NUMBER() OVER (PARTITION BY person, result ORDER BY id) AS max_count      
FROM TABLE

但它给了我 accumulative 个计数而不是 consecutive 个。

我应该怎么做才能进行连续计数？任何提示将不胜感激。提前致谢

Answer 1

这看起来像是经典的 gaps-and-islands 问题。在下面的查询中检查每个 CTE 的中间结果以了解发生了什么。

示例数据

我添加了人 3 有两个阳性结果序列，这样我们就可以找到最长的序列。

DECLARE @T TABLE (id int, person int, result int);
INSERT INTO @T (id, person, result) VALUES
(1 , 1, 0),
(2 , 1, 1),
(3 , 1, 1),
(4 , 2, 1),
(5 , 2, 0),
(6 , 1, 1),
(7 , 1, 0),
(8 , 2, 0),
(9 , 2, 0),
(10, 2, 0),
(11, 3, 0),
(12, 3, 1),
(13, 3, 1),
(14, 3, 1),
(15, 3, 1),
(16, 3, 0),
(17, 3, 1),
(18, 3, 1),
(19, 3, 0),
(20, 3, 0);

查询

WITH
CTE_RowNumbers
AS
(
    SELECT
        id, person, result
        ,ROW_NUMBER() OVER (PARTITION BY person ORDER BY ID) AS rn1
        ,ROW_NUMBER() OVER (PARTITION BY person, result ORDER BY ID) AS rn2
    FROM @T
)
,CTE_Groups
AS
(
    SELECT
        id, person, result
        ,rn1-rn2 AS GroupNumber
    FROM CTE_RowNumbers
)
,CTE_GroupSizes
AS
(
    SELECT
        person
        ,COUNT(*) AS GroupSize
    FROM CTE_Groups
    WHERE
        result = 1
    GROUP BY
        person
        ,GroupNumber
)
SELECT
    person
    ,MAX(GroupSize) AS max_count
FROM CTE_GroupSizes
GROUP BY person
ORDER BY person;

结果

+--------+-----------+
| person | max_count |
+--------+-----------+
|      1 |         3 |
|      2 |         1 |
|      3 |         4 |
+--------+-----------+

Answer 2

通过使用 Case 和 SUM 我们可以得到上面的结果

DECLARE @T TABLE (id int, person int, result int);
    INSERT INTO @T (id, person, result) VALUES
    (1 , 1, 0),
    (2 , 1, 1),
    (3 , 1, 1),
    (4 , 2, 1),
    (5 , 2, 0),
    (6 , 1, 1),
    (7 , 1, 0),
    (8 , 2, 0),
    (9 , 2, 0),
    (10, 2, 0)
    select 
    person,
    SUM(CASE WHEN RESULT = 1 then 1 else 0 END) 
     from @T
    GROUP BY person

记录结果的连续计数

Consecutive Count on Record Result

sql

sql-server

tsql

row-number

gaps-and-islands