updation of databae .

Dear gurus ,

I am designing one module pool prog for purchase ( lc in sd vx11n ) as my client requirement .

I have lot of fields , here I cant use update command for updation of databse in change mode like vx12n , because of lot of field . Is there any way so that system wl identify by itself any changes in any field , then only it update the FD document no .else message come data already saved .

I need your healp gurus , I am waiting for your valuable reply .

Regards .

Joy .