使用排名函数查找重复出现

Question

请帮助我生成以下我一直在努力解决的查询。假设我有一个简单的表格，其中包含月份编号以及该特定月份是否有任何失败事件的信息

生成示例数据的脚本如下：

WITH DATA(Month, Success) AS
(
    SELECT  1, 0 UNION ALL
    SELECT  2, 0 UNION ALL
    SELECT  3, 0 UNION ALL
    SELECT  4, 1 UNION ALL
    SELECT  5, 1 UNION ALL
    SELECT  6, 0 UNION ALL
    SELECT  7, 0 UNION ALL
    SELECT  8, 1 UNION ALL
    SELECT  9, 0 UNION ALL
    SELECT 10, 1 UNION ALL
    SELECT 11, 0 UNION ALL
    SELECT 12, 1 UNION ALL
    SELECT 13, 0 UNION ALL
    SELECT 14, 1 UNION ALL
    SELECT 15, 0 UNION ALL
    SELECT 16, 1 UNION ALL
    SELECT 17, 0 UNION ALL
    SELECT 18, 0
)

鉴于“重复失败”的定义：

如果在任何 6 个月期间至少 4 个月内发生事件失败，那么最后一个月出现此类失败是“重复失败”，我的查询应返回以下输出

Month   Success RepeatedFailure
1       0   
2       0   
3       0   
4       1   
5       1   
6       0       R1
7       0       R2
8       1   
9       0   
10      1   
11      0       R3
12      1   
13      0   
14      1   
15      0   
16      1   
17      0
18      0       R1

在哪里：

• R1 第 6 个月的第 -1 次重复故障（过去 6 个月内有 4 次故障）。
• R2 第 7 个月第 2 次重复失败（过去 6 个月内出现 4 次失败）。
• R3 第 11 个月 -3 次重复失败（过去 6 个月内失败 4 次）。

R1 - 在第 18 个月再次出现第 1 次重复故障，因为在过去 6 个报告周期中第一次发生新的重复故障时，重复故障应从头开始重新编号

重复失败是连续计算的，因为我必须根据它的数量应用适当的乘数：

• 第一次重复失败 - X2
• 第二次重复失败 - X4
• 第三次及多次重复失败 -X5。

Answer 1

我确信这可以改进，但它确实有效。我们基本上做了两次传递 - 第一次确定重复失败，第二次确定重复失败的种类。请注意，Intermediate2 绝对可以取消，我只是为了清楚起见将其分开。所有代码都是一个语句，我的解释是交错的：

;WITH DATA(Month, Success) AS
-- assuming your data  as defined (with my edit)
,Intermediate AS 
(
SELECT
    Month,
    Success,
    -- next column for illustration only
    (SELECT SUM(Success) 
     FROM DATA hist 
     WHERE curr.Month - hist.Month BETWEEN 0 AND 5) 
        AS SuccessesInLastSixMonths,
    -- next column for illustration only
    6 - (SELECT SUM(Success) 
     FROM DATA hist 
     WHERE curr.Month - hist.Month BETWEEN 0 AND 5) 
        AS FailuresInLastSixMonths,
    CASE WHEN 
            (6 - (SELECT SUM(Success) 
                    FROM DATA hist 
                    WHERE curr.Month - hist.Month BETWEEN 0 AND 5)) 
            >= 4 
            THEN 1
            ELSE 0 
    END AS IsRepeatedFailure
FROM DATA curr 
-- No real data until month 6
WHERE curr.Month > 5
)

至此，我们已经确定了每个月是否是重复失败，通过计算最多六个月内的失败（包括它）。

,Intermediate2 AS
(
SELECT 
    Month,
    Success,
    IsRepeatedFailure,
    (SELECT SUM(IsRepeatedFailure) 
        FROM Intermediate hist 
        WHERE curr.Month - hist.Month BETWEEN 0 AND 5) 
        AS RepeatedFailuresInLastSixMonths
FROM Intermediate curr
)

现在我们统计了截至目前的六个月内重复失败的次数

SELECT
    Month,
    Success,
    CASE IsRepeatedFailure 
        WHEN 1 THEN 'R' + CONVERT(varchar, RepeatedFailuresInLastSixMonths) 
        ELSE '' END
    AS RepeatedFailureText
FROM Intermediate2

所以我们可以说，如果这个月是重复失败，那么重复失败的基数是多少。

结果：

Month       Success     RepeatedFailureText
----------- ----------- -------------------------------
6           0           R1
7           0           R2
8           1           
9           0           
10          1           
11          0           R3
12          1           
13          0           
14          1           
15          0           
16          1           
17          0           
18          0           R1

(13 row(s) affected)

性能考虑将取决于您实际拥有多少数据。

Answer 2

;WITH DATA(Month, Success) AS
(
    SELECT  1, 0 UNION ALL
    SELECT  2, 0 UNION ALL
    SELECT  3, 0 UNION ALL
    SELECT  4, 1 UNION ALL
    SELECT  5, 1 UNION ALL
    SELECT  6, 0 UNION ALL
    SELECT  7, 0 UNION ALL
    SELECT  8, 1 UNION ALL
    SELECT  9, 0 UNION ALL
    SELECT 10, 1 UNION ALL
    SELECT 11, 0 UNION ALL
    SELECT 12, 1 UNION ALL
    SELECT 13, 0 UNION ALL
    SELECT 14, 1 UNION ALL
    SELECT 15, 0 UNION ALL
    SELECT 16, 1 UNION ALL
    SELECT 17, 0 UNION ALL
    SELECT 18, 0
)

SELECT DATA.Month,DATA.Success,Isnull(convert(Varchar(10),b.result),'') +         
Isnull(CONVERT(varchar(10),b.num),'') RepeatedFailure
FROM (
SELECT *, ROW_NUMBER() over (order by Month) num FROM 
( Select * ,(case  when (select sum(Success) 
from DATA where MONTH>(o.MONTH-6) and MONTH<=(o.MONTH)  ) <= 2 
and o.MONTH>=6 then 'R' else  '' end) result
from DATA o
) a where result='R'
) b 
right join DATA on DATA.Month = b.Month
order by DATA.Month