Oracle trigger if not updating

You do this by not including the columns in the SET clause of the UPDATE statement.When a record is processed from the inserted table, the computed, identity, or column can contain a dummy value to meet the NOT NULL column requirement, but the INSTEAD OF UPDATE trigger ignores those values and the correct values are set by SQL Server.This solution works because an INSTEAD OF UPDATE trigger does not have to process data from the inserted columns that are not updated.In the inserted table passed to an INSTEAD OF UPDATE trigger, the columns specified in the SET clause follow the same rules as the inserted columns in an INSTEAD OF INSERT trigger.For columns not specified in the SET clause, the inserted table contains the values as they existed before the UPDATE statement was issued.

INSTEAD OF UPDATE triggers can be defined on a view or table to replace the standard action of the UPDATE statement. I only want the trigger to work when a, b and d are updated.It would be best if I could say something like "update on table when column not like c." The c column is consistent throughout all of my 196 tables; the columns a,b and d are not. There are optional declaration and exception sections, like any other PL/SQL block, if required.The "dml-event" can be one or more of the following.