trigger question

[mkey]

Hi all,
Why we use REFERENCING in a trigger?
The following trigger contains the REFERENCING clause:

CREATE OR REPLACE TRIGGER C_BIR
BEFORE INSERT
ON schema.c_table
REFERENCING OLD AS OLD NEW AS NEW
FOR EACH ROW
BEGIN
SELECT c_SEQ.NEXTVAL INTO :NEW.ID FROM DUAL;
END;
/

What does the "REFERENCING OLD AS OLD NEW AS NEW" means and why we need to use it?

Thanks!

 

[sem]

By default :new and ld are used as record value BEFORE and AFTER statement execution. Though using REFERENCING clause you may use other words.

CREATE OR REPLACE TRIGGER C_BIR
BEFORE INSERT
ON schema.c_table
REFERENCING OLD AS FOO NEW AS BAR
FOR EACH ROW
BEGIN
IF :FOO.ID IS NULL THEN
SELECT c_SEQ.NEXTVAL INTO :BAR.ID FROM DUAL;
END IF;
END;

Regards, Dima

 

[jee]

So in otherwords, the REFERENCING clause in your trigger is not needed since you are using the standard NEW and OLD (but it doesn't hurt anything either).