Oracle 18c

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CREATE TABLE staging_tbl (id, name, age, email, remark) AS
SELECT 1, 'Alice', 42, 'alice@example.com', CAST(NULL AS VARCHAR2(200)) FROM DUAL UNION ALL
SELECT 2, 'Betty', 18, 'betty@example.com', CAST(NULL AS VARCHAR2(200)) FROM DUAL UNION ALL
SELECT 3, 'Carol', 27, 'carol@example.com', CAST(NULL AS VARCHAR2(200)) FROM DUAL UNION ALL
SELECT 4, 'Debra', 92, 'debra@example.com', CAST(NULL AS VARCHAR2(200)) FROM DUAL;
4 rows affected

-- Use PL/SQL since db<>fiddle does not support bind variables.
DECLARE
  v_id    STAGING_TBL.ID%TYPE    := 1;
  v_age   STAGING_TBL.AGE%TYPE   := 52;
  v_email STAGING_TBL.EMAIL%TYPE := 'angie@example.com';
  v_name  STAGING_TBL.NAME%TYPE  := 'Angie';
BEGIN

UPDATE staging_tbl
SET age    = v_age,
    email  = v_email,
    name   = v_name,
    remark = remark
             || CASE WHEN v_age   <> age   THEN ',age updated'   END
             || CASE WHEN v_email <> email THEN ',email updated' END
             || CASE WHEN v_name  <> name  THEN ',name updated'  END
WHERE id = v_id;

END;
/
1 rows affected

SELECT * FROM staging_tbl;


ID
NAME
AGE
EMAIL
REMARK


1
Angie
52
angie@example.com
,age updated,email updated,name updated

2
Betty
18
betty@example.com
null

3
Carol
27
carol@example.com
null

4
Debra
92
debra@example.com
null

ID	NAME	AGE	EMAIL	REMARK
1	Angie	52	angie@example.com	,age updated,email updated,name updated
2	Betty	18	betty@example.com	null
3	Carol	27	carol@example.com	null
4	Debra	92	debra@example.com	null