Postgres 14

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CREATE TABLE test (id INT, val1 INT, val2 INT);
INSERT INTO test VALUES (1,11,111), (2,22,222);
2 rows affected

CREATE FUNCTION fn_test() 
RETURNS TRIGGER
AS $fn_test$
BEGIN
        NEW.id := NEW.id * 10;
    RETURN NEW;
END;
$fn_test$ LANGUAGE plpgsql;
CREATE TRIGGER tr_test
BEFORE UPDATE ON test
FOR EACH ROW
WHEN (OLD.val1 <> NEW.val1)
EXECUTE FUNCTION fn_test();
SELECT * FROM test;
UPDATE test SET val1 = 33 WHERE id = 1;
UPDATE test SET val2 = 444 WHERE id = 2;
SELECT * FROM test;


id
val1
val2


1
11
111

2
22
222


1 rows affected

1 rows affected



id
val1
val2


10
33
111

2
22
444