SQL Server GROUP BY COUNT Consecutive Rows Only

Question

I have a table called DATA on Microsoft SQL Server 2008 R2 with three non-nullable integer fields: ID, Sequence, and Value. Sequence values with the same ID will be consecutive,

Answer 1

You can use Sequence - ROW_NUMBER() OVER (ORDER BY ID, Val, Sequence) AS g to create a group:

SELECT
  ID,
  MIN(Sequence) AS Sequence,
  Val,
  COUNT(*) AS cnt
FROM
(
  SELECT
    ID,
    Sequence,
    Sequence - ROW_NUMBER() OVER (ORDER BY ID, Val, Sequence) AS g,
    Val
  FROM
    yourtable
) AS s
GROUP BY
  ID, Val, g

Please see a fiddle here.