how to display shift according to the time?

Hi ,

I want to display shift a,b,c in accordance with the current time . for example,

0.15 AM to 7.15AM = ShiftA

7.15AM to 3.45PM = ShiftB

3.45PM to 11.00PM = ShiftC

The shift value should change dynamically with Time. How can i Achieve this ?

Thanks.