PostgreSQL/contrib/noupdate

noupdate
~~~~~~~~

 - trigger to prevent updates on single columns.


Example:
~~~~~~~

CREATE TABLE TEST ( COL1 INT, COL2 INT, COL3 INT );

CREATE TRIGGER BT BEFORE UPDATE ON TEST FOR EACH ROW
	EXECUTE PROCEDURE 
	noup ('COL1');

-- Now Try
INSERT INTO TEST VALUES (10,20,30);
UPDATE TEST SET COL1 = 5;