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