-- https://docs.oracle.com/en/database/oracle/oracle-database/23/lnpls/plsql-triggers.html
CREATE TABLE tbl_history ( d DATE, old_obj t, new_obj t)
/
CREATE OR REPLACE TRIGGER Tbl_Trg
  AFTER UPDATE ON tbl
  FOR EACH ROW
BEGIN
  INSERT INTO tbl_history (d, old_obj, new_obj)
  VALUES (SYSDATE, :OLD.OBJECT_VALUE, :NEW.OBJECT_VALUE);
END Tbl_Trg;
/