获取Oracle sql中的无效月份

CREATE TABLE months (
  month_number NUMBER,
  month_name VARCHAR2(20)
);

INSERT INTO months VALUES (1, 'January');
INSERT INTO months VALUES (2, 'February');
INSERT INTO months VALUES (3, 'March');
INSERT INTO months VALUES (4, 'April');
INSERT INTO months VALUES (5, 'May');
INSERT INTO months VALUES (6, 'June');
INSERT INTO months VALUES (7, 'July');
INSERT INTO months VALUES (8, 'August');
INSERT INTO months VALUES (9, 'September');
INSERT INTO months VALUES (10, 'October');
INSERT INTO months VALUES (11, 'November');
INSERT INTO months VALUES (12, 'December');

SELECT month_name
FROM months
WHERE month_number NOT IN (
  SELECT DISTINCT EXTRACT(MONTH FROM your_date_column)
  FROM your_table
);