查询下一个时间间隔

Question

我试图从mySQL表中查询上层可用的“时间范围”

+----+----------+---------+
| id | timefrom | timeto  | 
+----+----------+---------+
|  0 | 08:30    | 10:30   |
|  7 | 15:00    | 16:00   |
|  2 | 17:00    | 17:30   |
|  8 | 18:00    | 21:00   |
+----+----------+---------+

查询结果将是下一个可用的时间范围，即10:30到15:00

edit1：id不按顺序

谢谢！

Answer 1

我认为你需要这个：

select t1.`timeto`, min(t2.`timefrom`)
from
  yourtable t1 inner join yourtable t2
  on t1.`timeto`<t2.`timefrom`
group by t1.`timeto`
having
  not exists (select null from yourtable t3
              where t1.`timeto`<t3.`timeto`
              and min(t2.`timefrom`)>t3.`timefrom`)

（仅当间隔不重叠时才会起作用）

Answer 2

我想我会使用像

这样的东西

SELECT
    t1.*,
    MIN(t2.`timefrom`) AS 'next (timefrom)',
    TIMEDIFF(MIN(t2.`timefrom`),t1.`timeto`) AS 'interval'
FROM `the_table` t1
LEFT OUTER JOIN `the_table` t2
ON t2.`timefrom` > t1.`timeto`
GROUP BY t1.`timefrom`,t1.`timeto`
#HAVING `next` IS NOT NULL

取消注释最后一行与使用INNER JOIN而不是LEFT OUTER JOIN相同。我选择LOJ的原因是因为我想看表中的所有记录，但当然这取决于你。