Quick frequency tables bucketing on time in MySQL

mysql_time_frequency_tables

# date field is of type 'date'
mysql> SELECT YEAR(date) AS year, MONTH(date) AS month, count(*) AS count FROM my_table GROUP BY year, month ORDER BY year, month;
+------+-------+-------+
| year | month | count |
+------+-------+-------+
| 2008 |     6 |     1 |
| 2009 |     3 |     1 |
| 2009 |     5 |     2 |
| 2009 |     6 |     1 |
| 2009 |     7 |     1 |
| 2009 |     8 |     5 |
| 2009 |     9 |    10 |
| 2009 |    10 |     7 |
| 2009 |    11 |    35 |
| 2009 |    12 |    38 |
| 2010 |     1 |    39 |
| 2010 |     2 |   219 |
| 2010 |     3 |   129 |
| 2010 |     4 |   132 |
| 2010 |     5 |   107 |
| 2010 |     6 |    71 |
| 2010 |     7 |   102 |
| 2010 |     8 |    84 |
| 2010 |     9 |   671 |
| 2010 |    10 |   227 |
| 2010 |    11 |   161 |
| 2010 |    12 |   167 |
+------+-------+-------+

http://dev.mysql.com/doc/mysql/en/date-and-time-functions.html list all the ways to dissect a 'date' type. Other options include the day of the week, month, or year, the quarter, and the week of the year.