MySQL - select interval of every 2 hours from timestamp column

Question

How do you select every n-hours in a timestamp column? I am able to do so with 1 hour by grouping:

SELECT log_timestamp
FROM log
GROUP BY 
    DATE( log_timestamp ), 
    HOUR( log_timestamp )

Returns:

log_timestamp
2015-11-08 00:00:01
2015-11-08 01:00:01
2015-11-08 02:00:01
2015-11-08 03:00:01
...

Any ideas for how to do this by 2 or more hours?

log_timestamp
2015-11-08 00:00:01
2015-11-08 02:00:01
2015-11-08 04:00:01
2015-11-08 06:00:01
...

Answer 1

You can use INTEGER DIVISION:

SELECT L.log_timestamp 
FROM log L 
GROUP BY DATE( log_timestamp ), hour( log_timestamp ) DIV 2

SqlFiddleDemo