根据另一列中的值递增然后中断并重新开始

问题描述

我想增加一列，然后根据另一列中的值停止并重新开始.

I want to increment a column and then stop and start again based on a value in another column.

例如:

我有一张桌子:

CustomerID  YearMonth   True_False  
9000        2013-01-01   0
9001        2013-02-01   0
9002        2013-03-01   0
9003        2013-04-01   0
9004        2013-05-01   0
9005        2013-06-01   1
9006        2013-07-01   0
9007        2013-08-01   0
9008        2013-09-01   0
9009        2013-10-01   1
9010        2013-11-01   0

我想实现这一目标:

CustomerID  YearMonth   True_False  Sequence
9000        2013-01-01   0            1
9001        2013-02-01   0            2
9002        2013-03-01   0            3
9003        2013-04-01   0            4 
9004        2013-05-01   0            5
9005        2013-06-01   1            0
9006        2013-07-01   0            1
9007        2013-08-01   0            2
9008        2013-09-01   0            3
9009        2013-10-01   1            0
9010        2013-11-01   0            1

所以这是基于 True_False 列.当 True_False 为 0 时，中断并重新开始.( True_False = 0 ) 的 Sequence 值不必为 0，也可以为 NULL.

So this is based on True_False column. When True_False is 0 then break and start over again. Sequence value for ( True_False = 0 ) doesn't need to be 0 could be NULL as well.

推荐答案

试试这个:

SELECT CustomerID, YearMonth, True_False,
       CASE 
          WHEN True_False = 1 THEN 0
          ELSE ROW_NUMBER() OVER (PARTITION BY True_False, grp 
                                  ORDER BY YearMonth) 
       END AS Sequence
FROM (      
   SELECT CustomerID, YearMonth, True_False,
          ROW_NUMBER() OVER (ORDER BY YearMonth) - 
          ROW_NUMBER() OVER (PARTITION BY True_False 
                             ORDER BY YearMonth) AS grp
   FROM mytable ) AS t
ORDER BY YearMonth

查询计算字段grp，该字段标识具有相同True_False 值的连续记录的岛.在外部查询中使用此字段，我们可以枚举这些岛屿中包含的记录，从而获得所需的序列号.

The query calculates field grp which identifies islands of consecutive records having the same True_False value. Using this field in an outer query we can enumerate the records contained inside these islands and thus get the required sequence number.

此处演示

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