合并重叠的时间间隔，如何? [英] Merge overlapping time intervals, how?

问题描述

有人可以帮助我进行**合并数据间隔的查询吗?
例如:普通选择:

Anyone could help me in a query that **merge a interval of datas?
ex: Common select:

选择ID，date_start，date_end从甚至到ORDER BY date_start

SELECT id, date_start, date_end FROM evento ORDER BY date_start

我知道了:


来自此:


但想要查询返回以下内容:

I GOT THIS:


FROM THIS:


but a want a query that return this:

01-2013-10-11 08:00:00 2013-10-11 15:00:00
02-2013-10-11 16:00:00 2013-10-11 19:00:00

01 - 2013-10-11 08:00:00 2013-10-11 15:00:00
02 - 2013-10-11 16:00:00 2013-10-11 19:00:00

非常感谢！

推荐答案

您也可以尝试执行此查询(除了上述注释中的PM 77-1给出的解决方案以外，还有其他解决方案):

You may also try this query (once more solutions beside those given by PM 77-1 in the comment above) :

WITH RECURSIVE cte( id, date_start, date_end ) AS
(
  SELECT id, date_start, date_end
  FROM evento
  UNION 
  SELECT e.id,
         least( c.date_start, e.date_start ),
         greatest( c.date_end, e.date_end )
  FROM cte c
  JOIN evento e
  ON e.date_start between c.date_start and c.date_end
     OR 
     e.date_end between c.date_start and c.date_end
)
SELECT distinct date_start, date_end
FROM (
  SELECT id, 
         min( date_start) date_start, 
         max( date_end ) date_end
  FROM cte
  GROUP BY id
) xx
ORDER BY date_start;

演示---> http://www.sqlfiddle.com/#!12 /bdf7e/9

但是，对于巨大的表，此查询的性能可能会非常慢，并且某些过程方法的性能可能会更好.

Demo ---> http://www.sqlfiddle.com/#!12/bdf7e/9

however for huge table the performance of this query could be horribly slow, and some procedural approach might perform better.

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