How to disable the edit Button on gridview depends on status

Question

Hi Friends,
   i ve the application like that Travel request.aspx


departuredate = jquery date picker
from =textbox
to = textbox
lodge = textbox


add(after press the button ll on details on gridview)

submit
                  GRIDVIEW table

        (above insertion value shown here)

for above values stored on My database table structure is:



create table travel_request
(
claim_id int identity,
departuredate datetime,
from varchar(20),
to varchar(20)
is_approved varchar(30)

)


once the user press the submit means ll go to approver now travel_request table column is_approved="fresh" in these fresh status  user can edit the value from grid view.

once the approver given the approval now travel_request table column is_approved="approved " gidview edit button would be disable


how to make a code?