Mysql检索最近4分钟内插入的行

I want to be able to retrieve rows that were inserted into a mysql table within the last 4 minutes. It may help that I have got a mysql datetime field called 'when' and I insert into it the mysql time at the point of insertion with the now 'NOW()' e.g.

$query = "INSERT INTO user_actions SET user='" . $user_id . "'" .
             ", action='" . $server_action . "'" .
             ", `when`=NOW()";

Is there an elegant way to SELECT * FROM user_actions WHERE ... (age of the row is younger than 4 minutes and action = 'some value') Feel free to disregard the 'when' if it is not needed.

Regards, Stuart

SELECT * FROM user_actions 
WHERE `when` >= addtime(now(), '-00:04:00')

or

SELECT * FROM user_actions 
WHERE `when` >= now() - interval 4 minute

You can use DATE_ADD, see here for documentation.

Example:

SELECT * FROM `user_actions` WHERE `when` >= DATE_ADD( NOW(), INTERVAL -4 MINUTE )

SELECT * FROM user_actions 
WHERE `when` >= DATE_ADD(now(), INTERVAL -4 MINUTE)
and `action` ='someAction'