Mysql Time Difference

[kapiljain]

Dear All,

I require to calculate time difference. I require it to calculate total late coming hours of emplyoee every day. As my application automatically displays emplyoee reporting time when we gonna fill employee actual reporting time and time will be feeded in 12 hours so i have point that supposing employee's actual reporting time is 9.00 am and if he is reporting at 12.00 pm than how i will calculate time difference becuase it will come negative. Also i want how i will store am and pm in time field.or anyother alternate so that i can show am/pm in reports as well i can calculate time difference too.

Thanks...
//Kapil

[physics]

You should use a 24 hour clock, i.e. 1pm = 13.