Hello Raymond,

Datetime will force users to enter a valid date & time without much checking on your part, as long as the users don't balk at the default input structure. You can also peform math calculation fairly easily.

If you use a text field HH:MM you need to check the range for hours and minutes, and generally you would convert to a decimal version to do the math.

EX: 12:30 = 12.50 (divide minutes by 60) and you also have to account for time that breaks over a boundry:

02:00 - 10:00 = 4.00 (add 12 to the hours if it rolls over)

I've done it both ways, easier with datetime, users liked entering the text method better, but only because of the code enforcing the input was more flexible because it was custom.

Bob

>What is the best way to do calculations with time?
>
>I have a time sheet to do where the users enter the time started such as 8:30 and the end time such as 13:20.
>Should I use a character field for entry formated 99:99 or is a datetime better?
>Are there pre existing functions to do the calculations?
>
>Thanks in advance.
>
>Raymond Larche