mysql使用之前的值生成缺少的日期

CREATE TABLE dates (
    date_value DATE
);

INSERT INTO dates (date_value)
SELECT DATE('2021-01-01') + INTERVAL (a.a + (10 * b.a) + (100 * c.a)) DAY AS date
FROM (SELECT 0 AS a UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3) AS a
CROSS JOIN (SELECT 0 AS a UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3) AS b
CROSS JOIN (SELECT 0 AS a UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3) AS c
WHERE DATE('2021-01-01') + INTERVAL (a.a + (10 * b.a) + (100 * c.a)) DAY <= '2021-01-31';

SELECT d.date_value
FROM dates d
LEFT JOIN your_table t ON d.date_value = t.date_column
WHERE t.date_column IS NULL;