Question

Given the tables below, what is the best approach to (in both server-flavors):

Group all rows within a minute/hour/day and get the maximum column ‘CounterC’ ?

Example: Between ‘now’ and ‘now’ – 1 day, get Max(CounterC) for each hour.
Example2: Between ‘now’ and ‘now’ – 30 days, get Max(CounterC) for each day.

Obviously the rows have to be grouped, but how?

MS SQL

CREATE TABLE [dbo].[DE0000000D102D1D](
[index] [bigint] IDENTITY(1,1) NOT NULL,
[TimeStamp] [datetime] NOT NULL,
[CounterA] [bigint] NOT NULL,
[CounterB] [bigint] NOT NULL,
[CounterC] [bigint] NOT NULL,
[CounterD] [bigint] NOT NULL,
)

MySQL

CREATE TABLE `de0000000d102d1d` (
 `index` bigint(20) NOT NULL AUTO_INCREMENT,
 `TimeStamp` datetime NOT NULL,
 `CounterA` bigint(20) NOT NULL,
 `CounterB` bigint(20) NOT NULL,
 `CounterC` bigint(20) NOT NULL,
 `CounterD` bigint(20) NOT NULL,
 PRIMARY KEY (`index`)
)

Some example data:

index  TimeStamp                CounterA  CounterB  CounterC   CounterD
-----  -----------------------  --------  --------  ---------  --------
1      2011-03-07 14:25:32.000  0         1         347406352  916
2      2011-03-07 14:26:32.000  0         1         347407169  916
3      2011-03-07 14:27:32.000  0         1         347407978  916
4      2011-03-07 14:28:31.000  0         1         347408617  916
5      2011-03-07 14:29:31.000  0         1         347409087  916
6      2011-03-07 14:30:30.000  0         1         347409557  916
7      2011-03-07 14:31:09.000  0         1         347409845  916

Thanks in advance!

Edit: It is actually Max(CounterC) I want for each interval, not the sum.

Answer 1

For SQL Server

-- Last 30 days grouped by day
select dateadd(day, datediff(day, 0, D.[TimeStamp]), 0) as [day], 
       max(D.CounterC) as MaxC
from DE0000000D102D1D as D
where D.[TimeStamp] between dateadd(d, -30, getdate()) and getdate()
group by dateadd(day, datediff(day, 0, D.[TimeStamp]), 0)

-- Last day grouped by the hour
select dateadd(hour, datediff(hour, 0, D.[TimeStamp]), 0) as [Hour], 
       max(D.CounterC) as MaxC
from DE0000000D102D1D as D
where D.[TimeStamp] between dateadd(d, -1, getdate()) and getdate()
group by dateadd(hour, datediff(hour, 0, D.[TimeStamp]), 0)