How to increment a variable inside CASE WHEN clause? - sql

Question

I'm trying to make a new column with a variable that increments given a condition clause.
This is my query:
SELECT
[timestamp],
[load],
[timestamp] % 60 AS module,
group_by_column = CASE WHEN ([timestamp] % 60)= 0 then 1 else 0 end
FROM
table_01
And this is my return:
timestamp load module group_by_column
1432592618 24 38 0
1432592619 32 39 0
1432592620 21 40 0
1432592621 31 41 0
1432592622 28 42 0
1432592640 22 0 1
1432592641 31 1 0
1432592642 39 2 0
1432592643 33 3 0
1432592644 36 4 0
1432592649 32 9 0
1432592698 21 58 0
1432592700 25 0 1
1432592701 20 1 0
1432592702 27 2 0
1432592703 31 3 0
I need a table like this:
timestamp load module group_by_column
1432592618 24 38 0
1432592619 32 39 0
1432592620 21 40 0
1432592621 31 41 0
1432592622 28 42 0
1432592640 22 0 1
1432592641 31 1 1
1432592642 39 2 1
1432592643 33 3 1
1432592644 36 4 1
1432592649 32 9 1
1432592698 21 58 1
1432592700 25 0 2
1432592701 20 1 2
1432592702 27 2 2
1432592703 31 3 2
For Example, every time I found the condition [timestamp] % 60 = 0 is satisfied, I increment in the forth column.
I don't know if this is the best way to solve this problem, I just need an output as described below.
Thanks

Answer 1

In SQL Server 2012+, you would do a cumulative sum:
SELECT [timestamp], [load], [timestamp] % 60 AS module,
SUM(CASE WHEN [timestamp] % 60 = 0 THEN 1 ELSE 0 END) OVER
(ORDER BY timestamp) as group_by_column
FROM table_01;
In SQL Server 2008, I think you can get the same effect using dense_rank():
SELECT [timestamp], [load], [timestamp] % 60 AS module,
DENSE_RANK() OVER (ORDER BY [timestamp] / 60)
FROM table_01;

Answer 2

In case the counting integer should reflect the minutes that have passed since the first event, then the following will work:
SELECT [timestamp], [load], [timestamp] % 60 AS module,
([timestamp] / 60) - (SELECT min([timestamp]) / 60 FROM table_01) grp
FROM table_01;