Grupo de SQL Server por recuento de DateTime por hora?

Question

create table #Events 
(
    EventID int identity primary key, 
    StartDate datetime not null, 
    EndDate datetime not null 
) 
go 
insert into #Events (StartDate, EndDate) 
select '2007-01-01 12:44:12 AM', '2007-01-01 12:45:34 AM' union all 
select '2007-01-01 12:45:12 AM', '2007-01-01 12:46:34 AM' union all 
select '2007-01-01 12:46:12 AM', '2007-01-01 12:47:34 AM' union all 
select '2007-01-02 5:01:08 AM', '2007-01-02 5:05:37 AM' union all 
select '2007-01-02 5:50:08 AM', '2007-01-02 5:55:59 AM' union all 
select '2007-01-03 4:34:12 AM', '2007-01-03 4:55:18 AM' union all 
select '2007-01-07 3:12:23 AM', '2007-01-07 3:52:25 AM' 

(con perdón de http://www.sqlteam.com/article/working-with-time-spans-and-durations-in-sql-server para cosechar su sql base)

Estoy tratando de encontrar el recuento de los eventos que ocurrieron en una hora, por lo que el conjunto de resultados se vería así:

2007-01-01  12:00  3 
2007-01-02  5:00  2 
2007-01-03  4:00  1 
2007-01-07  3:00  1 

He estado jugando con dateadd y rondando y agrupando pero no obteniéndolo. ¿Alguien puede ayudar?

Gracias.

Answer 1

¿Qué le parece esto? Suponiendo SQL Server 2008:

SELECT CAST(StartDate as date) AS ForDate, 
     DATEPART(hour,StartDate) AS OnHour, 
     COUNT(*) AS Totals 
FROM #Events 
GROUP BY CAST(StartDate as date), 
     DATEPART(hour,StartDate) 

Para pre-2008:

SELECT DATEADD(day,datediff(day,0,StartDate),0) AS ForDate, 
     DATEPART(hour,StartDate) AS OnHour, 
     COUNT(*) AS Totals 
FROM #Events 
GROUP BY CAST(StartDate as date), 
     DATEPART(hour,StartDate) 

Esto se traduce en:

ForDate     | OnHour | Totals 
----------------------------------------- 
2011-08-09 00:00:00.000  12  3 

Answer 2

Como alternativa, sólo GROUP BY la hora, día:

SELECT CAST(Startdate as DATE) as 'StartDate', 
     CAST(DATEPART(Hour, StartDate) as varchar) + ':00' as 'Hour', 
     COUNT(*) as 'Ct' 
FROM #Events 
GROUP BY CAST(Startdate as DATE), DATEPART(Hour, StartDate) 
ORDER BY CAST(Startdate as DATE) ASC 

salida:

StartDate Hour Ct 
2007-01-01 0:00 3 
2007-01-02 5:00 2 
2007-01-03 4:00 1 
2007-01-07 3:00 1 

Answer 3

Encontré esto en otro lugar. Me gusta esta respuesta!

SELECT [Hourly], COUNT(*) as [Count] 
    FROM 
(SELECT dateadd(hh, datediff(hh, '20010101', [date_created]), '20010101') as [Hourly] 
    FROM table) idat 
GROUP BY [Hourly]