Как найти самый длинный непрерывный ряд событий с помощью SQL http://habrahabr.ru/post/270573/

days.sql

WITH
 
  -- This table contains all the distinct date 
  -- instances in the data set
  dates(date) AS (
    SELECT DISTINCT CAST(CreationDate AS DATE)
    FROM Posts
    WHERE OwnerUserId = ##UserId##
  ),
   
  -- Generate "groups" of dates by subtracting the
  -- date's row number (no gaps) from the date itself
  -- (with potential gaps). Whenever there is a gap,
  -- there will be a new group
  groups AS (
    SELECT
      ROW_NUMBER() OVER (ORDER BY date) AS rn,
      dateadd(day, -ROW_NUMBER() OVER (ORDER BY date), date) AS grp,
      date
    FROM dates
  )
SELECT
  COUNT(*) AS consecutiveDates,
  MIN(week) AS minDate,
  MAX(week) AS maxDate
FROM groups
GROUP BY grp
ORDER BY 1 DESC, 2 DESC

week.sql

WITH
  weeks(week) AS (
    SELECT DISTINCT datepart(year, CreationDate) * 100 
                  + datepart(week, CreationDate)
    FROM Posts
    WHERE OwnerUserId = ##UserId##
  ),
  groups AS (
    SELECT
      ROW_NUMBER() OVER (ORDER BY week) AS rn,
      dateadd(day, -ROW_NUMBER() OVER (ORDER BY week), week) AS grp,
      week
    FROM weeks
  )
SELECT
  COUNT(*) AS consecutiveWeeks,
  MIN(week) AS minWeek,
  MAX(week) AS maxWeek
FROM groups
GROUP BY grp
ORDER BY 1 DESC, 2 DESC