条纹的增量列

Question

如何使以下结果以黄色突出显示？

基本上我想要一个计算字段，当 VeganOption = 1 时递增 1，当 VeganOption = 0 时为零

我尝试使用以下查询，但使用分区在零后继续递增。我有点卡在这个上面。

SELECT [UniqueId]
      ,[Meal]
      ,[VDate]
      ,[VeganOption]
      , row_number() over (partition by [VeganOption] order by [UniqueId])
  FROM [Control]
  order by [UniqueId]

Table数据：

CREATE TABLE Control
    ([UniqueId] int, [Meal] varchar(10), [VDate] datetime, [VeganOption] int);

INSERT INTO Control ([UniqueId], [Meal], [VDate], [VeganOption])
VALUES
('1', 'Breakfast',' 2018-08-01 00:00:00', 1),
('2', 'Lunch',' 2018-08-01 00:00:00', 1),
('3', 'Dinner',' 2018-08-01 00:00:00', 1),
('4', 'Breakfast',' 2018-08-02 00:00:00', 1),
('5', 'Lunch',' 2018-08-02 00:00:00', 0),
('6', 'Dinner',' 2018-08-02 00:00:00', 0),
('7', 'Breakfast',' 2018-08-03 00:00:00', 1),
('8', 'Lunch',' 2018-08-03 00:00:00', 1),
('9', 'Dinner',' 2018-08-03 00:00:00', 1),
('10', 'Breakfast',' 2018-08-04 00:00:00', 0),
('11', 'Lunch',' 2018-08-04 00:00:00', 1),
('12', 'Dinner',' 2018-08-04 00:00:00', 1)
;

这适用于 SQL Server 2016+

Answer 1

这是 gaps-and-islands 的变体。

我喜欢用行号的不同来定义条纹。这看起来像

select c.*,
       (case when veganoption = 1
             then row_number() over (partition by veganoption, seqnum - seqnum_v order by uniqueid)
             else 0
        end) as veganstreak
from (select c.*,
             row_number() over (partition by veganoption order by uniqueid) as seqnum_v,
             row_number() over (order by uniqueid) as seqnum
      from c
     ) c;

为什么这行得通有点难以解释。但是，如果您查看子查询的结果，您将看到行号的差异如何定义您想要识别的条纹。剩下的只是应用 row_number() 来枚举膳食。

这里是Rextester.

Answer 2

一种方法是使用 CTE 来定义您的分组，然后对这些进行进一步的 ROW_NUMBER()，结果是：

WITH Grps AS(
    SELECT *,
           ROW_NUMBER() OVER (ORDER BY UniqueID ASC) - 
           ROW_NUMBER() OVER (PARTITION BY VeganOption ORDER BY UniqueID ASC) AS Grp
    FROM Control)
SELECT *,
       CASE VeganOption WHEN 0 THEN 0 ELSE ROW_NUMBER() OVER (PARTITION BY Grp ORDER BY UniqueID ASC) END
FROM Grps
ORDER BY UniqueId;

Answer 3

您可以使用 SUM 创建子组，然后 ROW_NUMBER:

WITH cte AS (
  SELECT [UniqueId]
      ,[Meal]
      ,[VDate]
      ,[VeganOption]
      ,sum(CASE WHEN VeganOption = 1 THEN 0 ELSE 1 END) 
         over (order by [UniqueId]) AS grp  --switching 0 <-> 1
  FROM [Control]
)
SELECT *,CASE WHEN VeganOption =0 THEN 0
        ELSE ROW_NUMBER() OVER(PARTITION BY veganOption, grp ORDER BY [UniqueId])
        END AS VeganStreak                  -- main group and calculated subgroup
FROM cte
order by [UniqueId];

Rextester Demo

条纹的增量列

Increment column for streaks

sql

sql-server

tsql

sql-server-2016

gaps-and-islands