Help on Trigger functions

Hi all,

I have a table something like this -

PointTable(PointName varchar, PointType integer, PointValue integer);

I have to write a trigger before UPDATE on this table. In the trigger function, I need to check which field of the table is going to be updated...based on this I need to do some operation.

CREATE FUNCTION Trg_UpdPointTable RETURNS TRIGGER AS'
BEGIN
        IF PointType is being modified THEN
                // do some operation.
        ELSIF PointValue is being modified THEN
                // Do some operation
        END IF;
END;

CREATE TRIGGER PTableTrg BEFORE UPDATE ON PointTable FOR EVERY ROW EXECUTE PROCEDURE Trg_UpdPointTable();

Is this functionality possible. I am using PostgreSQL version 7.4.3.

Thanks in advance.

Regards,
Pradeep