Two columns same value Inserted into the table using trigger or using with out trigger

Two columns same  value Inserted into the table:

create table test3
( number1 number(6,2),
number2 number(6,2),
total number(6,2) generated always as (number1+0) );

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Two columns same  value Inserted into the table using trigger 

create table test1
  (number1 decimal(6,2),
   number2 decimal(6,2),
   total decimal(6,2));

CREATE TRIGGER test1_bi
  BEFORE INSERT ON test1
  FOR EACH ROW
BEGIN
  IF :new.total is NULL THEN
    :NEW.TOTAL := :new.number1 ;
  END IF;
END test1_bi;

INSERT INTO test1(number1, number2) VALUES(1, 2);

SELECT * FROM test1;