Align values to 5 minute intervals I have values inserted with random intervals in the table. I would like to fetch the first (if exists) value in (say) 5 minutes interval. So is required to have 5 minutes column and the values column should express the first possible value before the next 5 minute range.
Using the aggregate function it is possible to get min, max, avg ... which is not the case here. I need the first possible value in the range. 

Id  TSDest                  Value
1   2019-02-18 08:31:00.000 3472
2   2019-02-18 08:35:00.000 3471
3   2019-02-18 08:39:00.000 3464
4   2019-02-18 08:43:00.000 3462
5   2019-02-18 08:47:00.000 3456
6   2019-02-18 08:51:00.000 3455
7   2019-02-18 08:55:00.000 3463
8   2019-02-18 08:59:00.000 3466
9   2019-02-18 09:04:00.000 3166


I need the values aligned to a constant time interval e.g. 5 minutes
(A plus feature would be to get the nearest timestamp value in the range).

Id  TSDest                  Value
1   2019-02-18 08:30:00.000 3472
2   2019-02-18 08:35:00.000 3471

4   2019-02-18 08:40:00.000 3462
5   2019-02-18 08:45:00.000 3456
6   2019-02-18 08:50:00.000 3455
7   2019-02-18 08:55:00.000 3463

9   2019-02-18 09:00:00.000 3166


Help appreciated,
Assuming seconds always are '00.000':

WITH cte AS ( SELECT Id, 
                     DATEADD(mi, -DATEPART(mi, TSDest) % 5, TSDest) TSDest, 
                     Value,
                     ROW_NUMBER() OVER (PARTITION BY DATEADD(mi, -DATEPART(mi, TSDest) % 5, TSDest) 
                                        ORDER BY TSDest ASC) rn
              FROM test )
SELECT Id, TSDest, Value
FROM cte
WHERE rn = 1
ORDER BY TSDest


fiddle



Added by OP

Thank you very much, this was very helpful.
BTW, because I had records with seconds and milliseconds, I had to add cast the time 
to "smalldatetime" which did the trick very well, 

WITH cte AS ( SELECT Id, 
                         cast(DATEADD(mi, -DATEPART(mi, TSDest) % 5, TSDest) as smalldatetime) TSDest, 
                         Value,
                         ROW_NUMBER() OVER (PARTITION BY cast(DATEADD(mi, -DATEPART(mi, TSDest) % 5, TSDest) as smalldatetime)  
                                            ORDER BY TSDest ASC) rn
                  FROM test )
    SELECT Id, TSDest, Value
    FROM cte
    WHERE rn = 1
    ORDER BY TSDest