Another thing to watch out for in this scenario is database triggers. (This is a common situation in Oracle Forms shops, where the default behavior of forms is to update all of the selected database columns as opposed to just the ones that changed).
As a general rule, it's smart to construct the WHEN clauses of database triggers to fire only when the values of the columns you care about are actually changing:
Wrong:
WHEN UPDATING(mycolumn)
Right (one possible method):
WHEN (NVL(OLD.mycolumn,some impossible value) != NVL(NEW.mycolumn,same impossible value))
HTH
Tim
