[SQL] Trigger function to know which fields are being updated

[Bernard Cheung]

I am writing a trigger function. How can I know which fields are being 
updated in the PL/SQL function?

For example I have a table here:

CREATE TABLE COMPANY (
 COMPANY_ID VARCHAR(10) NOT NULL,
 NAME VARCHAR(30),
 ADDRESS VARCHAR(30));
I want to write a trigger to block all update statements without updating 
NAME. I tried the following code block and it doesn't work:

 IF TG_OP = ''UPDATE'' THEN
    IF NEW.NAME IS NULL THEN
       RAISE NOTICE ''Field NAME must be provided!'';
    END IF;
 END IF;
Are there any functions like the Oracle's UPDATING() predicate?

Bernard Cheung

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