Mysql:在两个日期和时间之间寻找空的时间块? [英] Mysql : Finding empty time blocks between two dates and times?

问题描述

我想从数据库表中找出用户的可用性:

I wanted to find out user's availability from database table:

primary id | UserId | startdate        | enddate
1          | 42     | 2014-05-18 09:00 | 2014-05-18 10:00
2          | 42     | 2014-05-18 11:00 | 2014-05-18 12:00
3          | 42     | 2014-05-18 14:00 | 2014-05-18 16:00
4          | 42     | 2014-05-18 18:00 | 2014-05-18 19:00

让我们考虑上面插入的数据是用户的忙碌时间，我想从表中找出开始时间和结束时间之间的空闲时间间隔块.

Let's consider above inserted data is user's busy time, I want to find out free time gap blocks from table between start time and end time.

BETWEEN 2014-05-18 11:00 AND 2014-05-18 19:00;

让我在这里添加表格模式以避免混淆:

Let me add here schema of table for avoiding confusion:

Create Table availability (
  pid int not null,
  userId int not null,
  StartDate datetime,
  EndDate datetime
);

Insert Into availability values
  (1, 42, '2013-10-18 09:00', '2013-10-18 10:00'),
  (2, 42, '2013-10-18 11:00', '2013-10-18 12:00'),
  (3, 42, '2013-10-18 14:00', '2013-11-18 16:00'),
  (4, 42, '2013-10-18 18:00', '2013-11-18 19:00');

要求:我想找出免费间隔记录，例如:

REQUIREMENT: I wanted to find out free gap records like:

'2013-10-27 10:00' to '2013-10-28 11:00' - User is available for 1 hours and    
'2013-10-27 12:00' to '2013-10-28 14:00' - User is available for 2 hours and 
available start time is '2013-10-27 10:00' and '2013-10-27 12:00' respectively.

推荐答案

给你

SELECT t1.userId,
t1.enddate, MIN(t2.startdate),
MIN(TIMESTAMPDIFF(HOUR, t1.enddate, t2.startdate))
FROM user t1
JOIN user t2 ON t1.UserId=t2.UserId 
AND t2.startdate > t1.enddate AND t2.pid > t1.pid
WHERE
t1.endDate >= '2013-10-18 09:00'
AND t2.startDate <= '2013-11-18 19:00'
GROUP BY t1.UserId, t1.endDate

http://sqlfiddle.com/#!2/50d693/1

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