How to update the appraisel status and what is the relevent table?

Hi Experts,

In hap_main_document (Web dynpro component), how can we change the status based on date validation?

My requirement is : If current status is "2  In Planning", so after 12 April of  every year Status should change to "5  Completed" .

How to achieve the same by program.

I am new in web dynpro and HCM both.

Thanks in Advance.