Auto populate Duration field

Lucky1
Tera Guru

Hello all,

 

On the Change request, whenever the Actual End is populated by the system, then the difference between Actual Start and Actual End has to be auto populated in the Duration field (Which contains Days and Hours).

 

Note: Duration field backend name: (u_duration)

 

Can someone tell me how can I do this?

 

 

Regards,

Lucky