update optimized

I want to ask about solving my problem.I have depositors table with the following fields
-Owner
-Account
-Saldo_original
-saldo
-kurs
-interest
-amount
-description
the question is how to update the right so that the update process only once ..
I am doing is thisdepositors
update set owner = 'Januar' account = 'b' saldo_original = 5000 kurs = 9500 Interest = 0.5
update depositors set balance = kurs * saldo_original
update depositors set amount = balance * interest
update depositors set description = (case amount> 10,000,000 then 'Top depositors' else 'normal depositors') end
I want to fix the problem and update process is not only a 1 times not 4 times as above, i am trying to make one update but the results not successful.So .. how to optimized ..thanks before ..