How to pair date rows in mysql -

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how pair rows imperfecty in mysql? imperfect, meaning rows not paired in , out. sometimes, there 2 in 1 out or no out @ or 2 or more out 1 in or no in @ all. table this:

| id | action |        date         | +----+--------+---------------------+ |  1 | in     | 19.1.2012  15:41:52 | |  1 | out    | 19.1.2012  15:55:52 | |  2 | in     | 19.2.2012  15:55:52 | |  2 | out    | 19.2.2012  17:55:53 | |  1 | in     | 19.3.2012  15:55:54 | |  1 | in     | 19.3.2012  17:55:55 | |  1 | out    | 19.3.2012  19:55:56 | |  3 | in     | 19.4.2012  15:55:57 | |  3 | out    | 19.4.2012  17:55:58 | |  3 | out    | 19.4.2012  19:55:59 | +----+--------+---------------------+

the desired result this:

+----+--------+---------------------+ | id | action |        date         | +----+--------+---------------------+ |  1 | in     | 19.1.2012  15:41:52 | |  1 | out    | 19.1.2012  15:55:52 | |  2 | in     | 19.2.2012  15:55:52 | |  2 | out    | 19.2.2012  17:55:53 | |  1 | in     | 19.3.2012  17:55:55 | |  1 | out    | 19.3.2012  19:55:56 | |  3 | in     | 19.4.2012  15:55:57 | |  3 | out    | 19.4.2012  17:55:58 | +----+--------+---------------------+

this best desireed result

+----+---------------------+---------------------+ | id |       date_in       |      date_out       | +----+---------------------+---------------------+ |  1 | 19.1.2012  15:41:52 | 19.1.2012  15:55:52 | |  2 | 19.2.2012  15:55:52 | 19.2.2012  17:55:53 | |  1 | 19.3.2012  17:55:55 | 19.3.2012  19:55:56 | |  3 | 19.4.2012  15:55:57 | 19.4.2012  17:55:58 | +----+---------------------+---------------------+

here code, yields different result, can figure out error is? enter code here select c.e_id , cast(c.in_time datetime) in_time , c.out_time ( select if(@prev_id = d.id,@in_time,@in_time:=null) reset_in_time , @in_time := if(d.action = 'in',d.date,@in_time) in_time , if(d.action = 'out',d.date,null) out_time , @prev_id := d.id id ( select id, date_, action e join (select @prev_id := null, @in_time := null) f order id, date, action ) d ) c c.out_time not null order c.out_time enter code here

this selects in event a, out event b , uses left join eliminate row if there exists event c same id between them; in/out times don't have in or out between them.

select a.id, a.date date_in, b.date date_out  mytable join mytable b   on a.id = b.id , a.date < b.date left join mytable c   on a.id = c.id , c.date < b.date , c.date > a.date a.action = 'in' , b.action = 'out' , c.action null order a.date;

an sqlfiddle test with.


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