MySQL: Getting "busiest" or "most popular" hour from a datetime field?

Question

Consider the following table which has the fields - id (int) and date_created (datetime):

id       date_created

 1       2010-02-25 12:25:32
 2       2010-02-26 13:40:37
 3       2010-03-01 12:02:22
 4       2010-03-01 12:10:23
 5       2010-03-02 10:10:09
 6       2010-03-03 12:45:03

I want to know the busiest/most popular hour of the day for this set of data. In this example, the result I'm looking for would be 12.

Ideas?

Answer 1

To get just the most popular hour, use this query

select date_format( date_created, '%H' ) as `hour`
  from [Table]
 group by date_format( date_created, '%H' )
 order by count(*) desc
 limit 1;

If you want to look at all the data, go with this one

select count(*) as num_records
     , date_created
     , date_format( date_created, '%H' ) as `hour`
  from [Table]
 group by `hour`
 order by num_records desc;