Question

I’m going to try to explain this best I can I will provide more information if needed quickly.

I’m storing data for each hour in military time. I only need to store a days worth of data. My table structure is below

CREATE TABLE `onlinechart` (
  `id` int(255) NOT NULL AUTO_INCREMENT,
  `user` varchar(100) DEFAULT NULL,
  `daytime` varchar(10) DEFAULT NULL,
  `maxcount` smallint(20) DEFAULT NULL,
  `lastupdate` varchar(100) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=innodb AUTO_INCREMENT=2 DEFAULT CHARSET=latin1

The “user” column is unique to each user. So I will have list for each user.

The “daytime” column I’m having it store the day and hour together. So as for today and hour it would be “2116” so the day is 21 and the current hour is 16.

The “maxcount” column is what data for each hour. I’m tracking just one total number each hour.

The “lastupdate” column is just a timestamp im using to delete data that is 24 hours+ old.

I have the script running in PHP fine for the tracking. It keeps a total of 24 rows of data for each user and deletes anything older then 24hours. My problem is how would I go about a query that would start from the current hour/day and pull that past 24 hours maxcount and display them in order.

Thanks

Answer 1

You will run into an issue of handling this near the end of the year. It’s advisable you switch to using the native timestamp type of MySQL (described here: http://dev.mysql.com/doc/refman/5.0/en/datetime.html). Then you can grab max count by doing something such as:

SELECT * FROM onlinechart WHERE daytime >= ? ORDER BY maxcount

The question mark should be replaced by the timestamp – 86400 (number of seconds in a day).