Mysql查找约会之间的空闲时间段

Question

我正在尝试查找一天的空闲时间段，但我被困在正确的查询上。 开放时间或一天在每天 9:00 到 22:00 之间运行 以下查询返回全天的正确数据，除非当天的第一个预订是在 10:00，它不会返回 9 点之间的未预订时段:00 和 10:00，或者如果在 21:30 到 21:40 期间预订，则不会显示当天的最后一个时段是空闲的。

在为每一天和 set_id 解决这个问题时，我必须创建一个以 id=1 和 id=6 表示的一天开始和一天结束的 1 分钟条目。

我试图避免为每天和每个 set_id 创建这两个插入

CREATE TABLE bookings
(`id` int, `time_from` datetime, `time_to` datetime, `set_id` int);


INSERT INTO bookings
    (`id`, `time_from`, `time_to`, `set_id`)
VALUES
    (1, '2013-11-20 08:59:00', '2013-11-20 09:00:00', 6),
    (2, '2013-11-20 09:10:00', '2013-11-20 10:00:00', 6),
    (3, '2013-11-20 11:10:00', '2013-11-20 11:30:00', 6),
    (4, '2013-11-20 12:00:00', '2013-11-20 12:40:00', 6),
    (5, '2013-11-20 16:20:00', '2013-11-20 16:50:00', 6),
    (6, '2013-11-20 22:00:00', '2013-11-20 22:01:00', 6)
;

SELECT Available_from, Available_to
FROM (
    SELECT @lasttime_to AS Available_from, time_from AS Available_to, @lasttime_to := time_to
    FROM (SELECT time_from, time_to
          FROM bookings
          WHERE set_id = 6
            AND time_to >= '2013-11-20 08:59'
            AND time_from < '2013-11-20 22:01'
      ORDER BY time_from) e
    JOIN (SELECT @lasttime_to := NULL) init) x
WHERE Available_to > DATE_ADD(Available_from, INTERVAL 9 MINUTE);


|      AVAILABLE_FROM |                    AVAILABLE_TO |
|---------------------|---------------------------------|
| 2013-11-20 09:00:00 | November, 20 2013 09:10:00+0000 |
| 2013-11-20 10:00:00 | November, 20 2013 11:10:00+0000 |
| 2013-11-20 11:30:00 | November, 20 2013 12:00:00+0000 |
| 2013-11-20 12:40:00 | November, 20 2013 16:20:00+0000 |
| 2013-11-20 16:50:00 | November, 20 2013 22:00:00+0000 |

任何帮助将不胜感激。

http://www.sqlfiddle.com/#!2/b30a0/2

    CREATE TABLE `days` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `date` date NOT NULL,
  `time_from` datetime NOT NULL,
  `time_to` datetime NOT NULL,
  `step` int(11) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;


INSERT INTO `days` (`id`, `date`, `time_from`, `time_to`, `step`)
VALUES
    (1, '2013-11-20', '2013-11-20 09:00:00', '2013-11-20 22:00:00', 10),
    (2, '2013-11-21', '2013-11-21 09:00:00', '2013-11-21 22:00:00', 10);

再靠近一点！

INSERT INTO `bookings` (`id`, `date`, `time_from`, `time_to`, `set_id`, `name`, `email`, `telephone`, `amount`, `notes`, `is_paid`, `is_booked`)
VALUES
    (25, '2013-11-20', '2013-11-20 09:10:00', '2013-11-20 09:30:00', 1, '', '', '', NULL, NULL, 0, 0),
    (26, '2013-11-20', '2013-11-20 10:30:00', '2013-11-20 11:30:00', 1, '', '', '', NULL, NULL, 0, 0),
    (27, '2013-11-20', '2013-11-20 12:30:00', '2013-11-20 13:20:00', 1, '', '', '', NULL, NULL, 0, 0),
    (29, '2013-11-20', '2013-11-20 15:00:00', '2013-11-20 16:40:00', 1, '', '', '', NULL, NULL, 0, 0);

这就是我得到的

availableFrom         availableTo
9:00                  2013-11-20 09:10:00
2013-11-20 09:30:00       2013-11-20 10:30:00
2013-11-20 11:30:00       2013-11-20 12:30:00
9:00                  2013-11-20 15:00:00
2013-11-20 15:00:00       22:00

Answer 1

一种可能的选择是将表格与自身进行左连接：

select (case when ltime_to is null then '9:00' else ltime_to end) as availableFrom,
rtime_from as availableTo
from (select l.time_to as ltime_to, r.time_from as rtime_from from bookings r 
left join bookings l on l.id=r.id-1) lr
union
select max(time_from) as availableFrom, '22:00' as availableTo from bookings