Can you explain your problem? I don't understand how do you define your business rules.
Why are you using char(10) instead of a proper data type for time?
Luis C.
General Disclaimer:
Are you seriously taking the advice and code from someone from the internet without testing it? Do you at least understand it? Or can it easily kill your server?
How to post data/code on a forum to get the best help: Option 1 / Option 2