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copied!<p>Add a Cron or Scheduled task that executes at your lowest common interval (5 minutes? 1 minute?).</p> <p>The scheduled task should query a database table that holds info on the frequency of the user's task. I would express frequency in seconds, then use a UNIX timestamp to determine eligibility for execution. The computation is then somewhat easy:</p> <ul> <li>Find the current time, rounded down to nearest common interval (assuming a 60-second interval): NOW = TIMESTAMP - (TIMESTAMP % 60)</li> <li>Find users whose interval is an even divisor of the current time period</li> </ul> <p>The table could look like this:</p> <pre><code>CREATE TABLE `scheduled_tasks` ( `id` int(7) unsigned NOT NULL auto_increment, `user_id` int(7) unsigned NOT NULL, `task` varchar(32) NOT NULL, `interval` int(10) NOT NULL, `date_start` date NOT NULL default '0000-00-00', `date_end` date NOT NULL default '2030-12-31', -- Hopefully you won't be still maintaining this app PRIMARY KEY (`id`) ) ; INSERT INTO `scheduled_tasks` (user_id, task, interval, date_start, date_end ) VALUES (1, 'standard_job', 5*60, '2009-06-01', '2009-08-01'), (2, 'standard_job', 10*60, CURDATE(), CURDATE() ), (3, 'standard_job', 24*60*60, '2009-06-01', '2009-08-01') </code></pre> <p>To find jobs to run, this query could work:</p> <pre><code>SELECT `user_id`, `task` FROM `scheduled_tasks` WHERE (UNIX_TIMESTAMP() - (UNIX_TIMESTAMP() % 60 ) ) % `interval` = 0 AND CURDATE() BETWEEN `date_start` AND `date_end` </code></pre> <p>That comes back with a list of users/tasks to run. You can add multiple entries per user if necessary.</p>

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