Oracle 21c

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ALTER SESSION SET NLS_DATE_FORMAT = 'YYYY-MM-DD HH24:MI:SS';
CREATE TABLE table_name (id, date_column, number_of_months_column) AS
SELECT 1, DATE '2024-01-01', 3 FROM DUAL UNION ALL
SELECT 2, DATE '2024-03-31', 1 FROM DUAL;
2 rows affected

SELECT ADD_MONTHS(date_column, -number_of_months_column)
FROM   table_name;

ADD_MONTHS(DATE_COLUMN,-NUMBER_OF_MONTHS_COLUMN)

2023-10-01 00:00:00

2024-02-29 00:00:00

SELECT date_column - number_of_months_column * INTERVAL '1' MONTH
FROM   table_name
WHERE  id = 1;

DATE_COLUMN-NUMBER_OF_MONTHS_COLUMN*INTERVAL'1'MONTH

2023-10-01 00:00:00

SELECT date_column - number_of_months_column * INTERVAL '1' MONTH
FROM   table_name
WHERE  id = 2;
ORA-01839: date not valid for month specified