MySQL 查询以选择按 30 天间隔分组的最小日期时间

这是一些转储数据..

CREATE TABLE `customer` (
  `approve_datetime` datetime DEFAULT NULL,
  `created_date` date DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

INSERT INTO `customer` (`approve_datetime`, `created_date`)
VALUES
    ('2015-08-20 04:43:00','2015-08-20'),
    (NULL,'2015-09-03'),
    ('2015-09-17 02:17:00','2015-09-17'),
    (NULL,'2015-09-29'),
    ('2015-09-29 12:44:00','2015-09-29'),
    ('2015-10-08 03:09:00','2015-10-08'),
    ('2016-01-20 08:59:00','2016-01-19'),
    ('2016-05-03 09:38:00','2016-05-02'),
    ('2016-07-15 11:06:00','2016-07-15'),
    (NULL,'2016-08-30'),
    ('2016-10-18 12:55:00','2016-10-18'),
    (NULL,'2017-01-08'),
    (NULL,'2017-02-02'),
    ('2017-02-13 02:58:00','2017-02-13');

这是我当前的查询，它没有正确处理 30 天分组.

Here is my current query which doesn't handle the 30 day groupings correctly.

SELECT a.*
FROM customer a
WHERE a.approve_datetime IN (
        SELECT MIN(b.approve_datetime) 
        FROM customer b 
        WHERE b.created_date BETWEEN a.created_date 
            AND DATE_ADD(a.created_date, INTERVAL 30 DAY)
    )

这给了我以下内容.

+---------------------+--------------+
| approve_datetime    | created_date |
+---------------------+--------------+
| 2015-08-20 04:43:00 | 2015-08-20   |
| 2015-09-17 02:17:00 | 2015-09-17   |
| 2015-09-29 12:44:00 | 2015-09-29   |
| 2015-10-08 03:09:00 | 2015-10-08   |
| 2016-01-20 08:59:00 | 2016-01-19   |
| 2016-05-03 09:38:00 | 2016-05-02   |
| 2016-07-15 11:06:00 | 2016-07-15   |
| 2016-10-18 12:55:00 | 2016-10-18   |
| 2017-02-13 02:58:00 | 2017-02-13   |
+---------------------+--------------+

可以更改查询以获得以下结果吗?

Can the query be altered to achieve the following results?

+---------------------+--------------+
| approve_datetime    | created_date |
+---------------------+--------------+
| 2015-08-20 04:43:00 | 2015-08-20   |
| 2015-09-29 12:44:00 | 2015-09-29   |
| 2016-01-20 08:59:00 | 2016-01-19   |
| 2016-05-03 09:38:00 | 2016-05-02   |
| 2016-07-15 11:06:00 | 2016-07-15   |
| 2016-10-18 12:55:00 | 2016-10-18   |
| 2017-02-13 02:58:00 | 2017-02-13   |
+---------------------+--------------+

请注意，created_date 为 2015-09-17 和 2015-10-08 的记录已被删除，因为它们距上一条记录的 30 天之内是该特定组的最短日期.2015-08-20 + 30 天从第一组开始，2015-08-20 是该组的最短日期.

Notice that records with created_date's 2015-09-17 and 2015-10-08 have been removed because they are within 30 days of the previous record which is the minimum date for that particular group. 2015-08-20 + 30 days starts off the first group with 2015-08-20 being the min date for that group.

我希望我想要实现的目标是有意义的.

I hope what I'm trying to achieve makes sense.