如何对连续范围进行分组

Question

我知道一些基本的 SQL，但这个超出了我的能力范围。我看了高低，但没有骰子。我需要查看以下数据，我可以在应用程序层代码中执行此操作。但不幸的是，对于这一特定的情况，代码必须放在数据层中。

我正在使用 T-SQL。

表

Date      Crew       DayType
01-02-11  John Doe  SEA  
02-02-11  John Doe  SEA  
03-02-11  John Doe  SEA  
04-02-11  John Doe  HOME  
05-02-11  John Doe  HOME  
06-02-11  John Doe  SEA 

我需要这样的视图

DateFrom  DateTo    Name      DayType
01-02-11  03-02-11  John Doe  SEA
04-02-11  05-02-11  John Doe  HOME
06-02-11  06-02-11  John Doe  SEA

不幸的是，应用程序层需要基表才能采用所示的格式。这可以在查询中执行吗？

Answer 1

WITH    q AS
        (
        SELECT  *,
                ROW_NUMBER() OVER (PARTITION BY crew, dayType ORDER BY [date]) AS rnd,
                ROW_NUMBER() OVER (PARTITION BY crew ORDER BY [date]) AS rn
        FROM    mytable
        )
SELECT  MIN([date]), MAX([date]), crew AS name, dayType
FROM    q
GROUP BY
        crew, dayType, rnd - rn

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Answer 2

WITH grouped AS (
  SELECT
    *,
    grp = DATEDIFF(day, 0, Date) -
          ROW_NUMBER() OVER (PARTITION BY Crew, DayType ORDER BY Date)
  FROM @testtable
)
SELECT
  DateFrom = MIN(Date),
  DateTo = MAX(Date),
  Name = Crew,
  DayType
FROM grouped
GROUP BY Crew, DayType, grp;

基本上与 Quassnoi 的解决方案相同，但少使用一个 ROW_NUMBER 会产生更好的执行计划。

Answer 3

SELECT MIN(Date) AS DateFrom,MAX(Date) AS DateTo, Crew, DayType FROM yourTableName GROUP BY Crew, DayType

Answer 4

像这样的东西：

SELECT Crew, DayType, MIN(Date) AS SomeDate1, MAX(Date) AS SomeDate2 
FROM Mytable 
GROUP BY Crew, DayType

Answer 5

Select Min(Date) DateFrom, Max(Date) DateTo, Crew Name,DayType From Mytable Group By Crew,DayType 

试试这个。