gruppo DateTime per data e l'ora

Question

ho un datetime chiamato activity_dt ei dati si presenta così:

2/5/2013 9:24:00 AM 
2/7/2013 7:17:00 AM 

Come faccio gruppo in base alla data e l'ora?

Answer 1

SQL Server:

SELECT [activity_dt], count(*) 
FROM table1 
GROUP BY DATEPART(day, [activity_dt]), DATEPART(hour, [activity_dt]); 

Oracle:

SELECT [activity_dt], count(*) 
FROM table1 
GROUP BY TO_CHAR(activity_dt, 'DD'), TO_CHAR(activity_dt, 'hh'); 

MySQL:

SELECT [activity_dt], count(*) 
FROM table1 
GROUP BY hour(activity_dt) , day(activity_dt) 

Answer 2

SELECT [activity_dt], COUNT(*) as [Count] 
    FROM 
(SELECT dateadd(hh, datediff(hh, '20010101', [activity_dt]), '20010101') as [activity_dt] 
    FROM table) abc 
GROUP BY [activity_dt] 

Answer 3

Utilizzando MySQL faccio di solito in questo modo:

SELECT count(id), ... 
FROM quote_data 
GROUP BY date_format(your_date_column, '%Y%m%d%H') 
order by your_date_column desc; 

o nella stessa idea, se avete bisogno di uscita data/ora:

SELECT count(id) , date_format(your_date_column, '%Y-%m-%d %H') as my_date 
FROM your_table 
GROUP BY my_date 
order by your_date_column desc; 

Se si specifica un indice sul vostro colonna della data, MySQL dovrebbe essere in grado di usarlo per accelerare le cose un piccolo.