Oracle 21c

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CREATE TABLE tab(
    Test1     INT, 	
    Test2     VARCHAR(30)
);
INSERT ALL 
    INTO tab VALUES(1, 	'ABC')
    INTO tab VALUES(2, 	'DEF')
SELECT * FROM DUAL
2 rows affected

INSERT INTO tab
SELECT Test1 + COUNT(*) OVER(), Test2 FROM tab;
2 rows affected

SELECT * FROM tab


TEST1
TEST2


1
ABC

2
DEF

3
ABC

4
DEF