Question

我查询了以下表格结构。

ID  Date        Before value    After value
1   2014-04-25  Win             Loss
1   2014-04-30  Loss            Win
1   2014-08-18  Win             Loss
1   2014-08-27  Loss            Remise
1   2014-09-05  Remise          Loss
2   2014-05-25  Win             Remise
2   2014-06-07  Remise          Win
2   2014-06-20  Win             Loss

作为我的select语句的输出，我想要以下结果：

ID  Start_Date  End_Date    After value
1   start       2014-04-25  Win
1   2014-04-26  2014-04-30  Loss
1   2014-05-01  2014-08-18  Win
1   2014-08-19  2014-08-27  Loss
1   2014-08-28  2014-09-05  Remise
1   2014-09-06  current     Loss
2   start       2014-05-25  Win
2   2014-05-26  2014-06-07  Remise
2   2014-06-08  2014-06-20  Win
2   2014-06-21  current     Loss

当然，该表有1000条记录需要正确。我尝试了排名和加入，但没有运气。如果有下一行，我需要将此值检索为开始日期+1。

http://sqlfiddle.com/#!2/520b13/2

Answer 1

此方法使用MySql内联变量来保留最后一个ID以及与下一条记录进行比较的最后日期。

SELECT
      t.id,
      IF( @LastID = t.id, @LastDate, 'start     ' ) as StartDate,
      IF( NOT t.date = t2.date, t.date, 'current   ' ) as EndDate,
      t.after_value,
      @LastID := t.id as saveForNextLineID,
      @LastDate := t.date + INTERVAL 1 day as saveForNextDate
   from
      the_table t
         left join ( select id, max( date ) as date
                        from the_table
                        group by id ) t2
            ON t.id = t2.id,
      (select @LastID := 0, @LastDate := 'start     ' ) sqlvars
   order by
      t.id, 
      t.date

SQL Fiddle sample

Answer 2

类似的东西：

select t1.id, 
       (select max(date) + interval '1' day
        from the_table t2
        where t2.date < t1.date
          and t2.id = t1.id) as start_date,
       t1.date as end_date,
       t1.after_value
from the_table t1
order by t1.id, t1.date;

SQLFiddle：http://sqlfiddle.com/#!2/8905a/3

Answer 3

在某些行之间进行读取，但您可以使用UNION手动添加开始日期和结束日期，例如：

select * from mytable
union 
select DISTINCT ID,'2000-01-01' as `Date`,`Before value`,``After value` from mytable
union 
select DISTINCT ID,NOW() as `Date`,`Before value`,``After value` from mytable

尝试在子选择中弹出这个并在其上运行分组代码。

MySQL SELECT输出同一行中每个id的下一个日期

3 个答案: