Trigger updating column

This increases the code and also oracle has to check each 100 column's values to find out whether it is being updated.

Returns a Boolean value that indicates whether an INSERT or UPDATE attempt was made on a specified column of a table or view.

UPDATE() is used anywhere inside the body of a Transact-SQL INSERT or UPDATE trigger to test whether the trigger should execute certain actions.

This returns a bit pattern that indicates which columns were inserted or updated.

IF UPDATE returns the TRUE value in INSERT actions because the columns have either explicit values or implicit (NULL) values inserted.