Group By Date Range of Sequenced Only

问题

I am trying to generate a date range sequence and put date in second row if sequencing is break.

fldDate        TotalNo
2015-04-01     10
2015-04-02     10
2015-04-03     10
2015-04-04     10
2015-04-05     10
2015-04-06     10
2015-04-07     10
2015-04-08     10
2015-04-09     12
2015-04-10     12
2015-04-11     12
2015-04-12     12
2015-04-20     12
2015-04-21     12
2015-04-22     12
2015-04-23     12
2015-04-24     12
2015-04-25     12

I am really stumped

I want this table as

StartDate      EndDate      TotalNo
2015-04-01     2015-04-08   10
2015-04-09     2015-04-12   12
2015-04-20     2015-04-25   12

Means Either date range breaks or TotalNo change It should create a new row.

I have done it but its not working completely I am doing like

SELECT MIN(fldDate) AS StartDate,
       MAX(fldDate) AS EndDate,
       TotalNo
FROM dbo.tbl1
GROUP BY TotalNo
ORDER BY fldDate

It will create like

StartDate      EndDate      TotalNo
2015-04-01     2015-04-08   10
2015-04-09     2015-04-25   12

回答1:

You can identify the groups by subtracting an integer sequence from the fldDate -- such as provided by row_number(). Consecutive dates will have the same value after the subtraction. The rest is just group by:

select min(fldDate) as StartDate, max(fldDate) as EndDate, TotalNo
from (select t.*,
             dateadd(day,
                     - row_number() over (partition by TotalNo order by fldDate),
                     fldDate) as grp
      from table t
     ) t
group by TotalNo, grp
order by StartDate, TotalNo;

来源：https://stackoverflow.com/questions/29472414/group-by-date-range-of-sequenced-only