MySQL in a Nutshell, 2nd Edition

Name

HOUR()

Synopsis

HOUR(time)

This function returns the hour for the time given. For columns containing the time of day (e.g., DATETIME), the range of results will be from 0 to 23. For TIME data type columns that contain data not restricted to day limits, this function may return values greater than 23. Here is an example:

SELECT appt_id, appointment, 
HOUR(appointment) AS 'Hour of Appointment'
FROM appointments
WHERE client_id = '3992'
AND appointment > CURDATE( );

+---------+---------------------+---------------------+
| appt_id | appointment         | Hour of Appointment |
+---------+---------------------+---------------------+
| 8393    | 2008-03-15 13:00:00 |                  13 | 
+---------+---------------------+---------------------+

This statement is selecting the upcoming appointment for a particular client. The hour is returned in military time (i.e., 13 is 1 P.M.).