The easiest (and most reliable) way to store the time in a database table is with a timestamp. It is also the most convenient way of working out time scales as you don't have to do calculations in base 60. In MySQL this is accomplished by the UNIXTIME() function, which can be reversed by using another MySQL function called FROM_UNIXTIME().
However, you can sometimes be left with timestamps in your code and the task of trying to figure out what to do with them.
The first problem is trying to convert a timestamp into a date. So here is a PHP function that does this.