How update area field when geometry is updated

Question

hi all,
plz can someone help me to find solution or give me a way to solve my problem
i would like to create procedure to recalculate the area of geom and insert it the value in the specified field when the geom is updated.
I try 2 methods but no one works, the error appears if i update the geometry of parcel
------------------------------------------PL/SQL------------------------------------
----------------------------------------Oracle 9i---------------------------------------
CREATE OR REPLACE TRIGGER "GIS"."TRG_PARCEL" BEFORE
INSERT
OR UPDATE ON "PARCEL" FOR EACH ROW DECLARE
BEGIN
IF INSERTING THEN
select SDO_GEOM.sdo_area(geom,0.05) into :new.fld_AREA
from parcel where id_parcel = (select max(id_parcel) from PARCEL) ;
ELSIF UPDATING THEN
-----------------1st case to try ------------------------------
UPDATE PARCEL a
SET fld_AREA = (select SDO_GEOM.sdo_area(a.geom,0.05)
from parcel a where NOT SDO_GEOM.RELATE(a.geom,'EQUAL',val_new,0.005) = 'EQUAL' )
WHERE NOT SDO_GEOM.RELATE(a.geom,'EQUAL',val_new,0.005) = 'EQUAL';
-----------------2nd case to try ------------------------------
SELECT SDO_GEOM.SDO_AREA(c.geom, m.diminfo)
into :new.fld_AREA
FROM PARCEL c, user_sdo_geom_metadata m
WHERE m.table_name = 'PARCEL' AND m.column_name = 'GEOM'
AND old.geom <> :new.geom ;
end if;
end;
thnx for all
Geomaticien TN

Answer 1

Hello,
You may try the following:
CREATE OR REPLACE TRIGGER "GIS"."TRG_PARCEL" BEFORE
INSERT OR UPDATE ON "PARCEL" FOR EACH ROW DECLARE
BEGIN
:NEW.fld_AREA := SDO_GEOM.sdo_area(:NEW.GEOM,0.05);
END;
Thanks,
Ying
Edited by: user704655 on Jul 22, 2009 11:37 AM