this is arafat

["arafat uddin" <arafat.cse@xxxxxxxxx>]

sir,
            my problem is that,
in my project i have a  page call  stock.where every day  stock will be
change .
cause product  enter in the stock and product out form the stock
so,stack will be change when product will enter and out.
thats why i hav to use UPDATE statement .
plz write to me what kind of UPDATE statemnt i have to write.


For Example:  Balance  100 (caton)
                      product  enter 50  (caton)=stock(100+50)=150 (caton)
                      product   out   50 (caton)=stock(150-50)=100 (caton);