SQL count how many times status appear in succession

Question

I have a table with list of cases, and a list of status that they have:

Case ID | Date       | Status
------  | ---------- |-------
   x    | 2016-11-01 | Open
   x    | 2016-11-03 | Hold
   x    | 2016-11-04 | Hold
   x    | 2016-11-05 | Open
   x    | 2016-11-08 | Hold
   x    | 2016-11-15 | Processing
   x    | 2016-11-16 | Done

I want to indicate that there is a new record but status for the same case remained the same:

Case ID | Date       | Status     | count
------  | ---------- |----------  |------
   x    | 2016-11-01 | Open       |  1 
   x    | 2016-11-03 | Hold       |  1
   x    | 2016-11-04 | Hold       |  2
   x    | 2016-11-05 | Open       |  1
   x    | 2016-11-08 | Hold       |  1
   x    | 2016-11-15 | Processing |  1
   x    | 2016-11-16 | Done       |  1

If I do something like this:

SELECT * 
FROM
    (SELECT 
         ROW_NUMBER() OVER  (partition by [Case ID], [status] ORDER BY Date) AS Row, 
         ID, Status, Date 
     FROM 
         Cases) AS C
WHERE 
    ID = x
ORDER BY
    Date

it doesn't take into account that the last 'Hold' was after the 'Open' and puts number 3 though I need number 1.

Answer 1

You need to detect islands of successive records having the same status value and consume the 'island id' in the PARTITION BY clause of a ROW_NUMBER window function:

SELECT  [Case ID], [Date], [status],
        ROW_NUMBER() OVER (PARTITION BY [Case ID], [status], grp ORDER BY [Date]) AS [count]
FROM (
   SELECT  [Case ID], [Date], [status], 
           ROW_NUMBER() OVER (PARTITION BY [Case ID] ORDER BY [Date]) -
           ROW_NUMBER() OVER (PARTITION BY [Case ID], [status] ORDER BY [Date]) AS grp   
   FROM Cases) AS t
ORDER BY [Date]

Answer 2

You can try below also..

SELECT  CASEID,
       DATE,
       STATUS,
     CASE WHEN RNO<>0 THEN  (rno+r) ELSE 1 END
            FROM
        (
SELECT CASEID,
       DATE,
       STATUS,
       CASE
         WHEN STATUS = LAG(STATUS)
                         OVER (
                           PARTITION BY CASEID
                           ORDER BY CASEID,date) THEN 1
         ELSE 0
       END RNO,
       ROW_NUMBER() OVER( partition by date,status ORDER BY DATE,status) R
FROM   #TABLE1 )A