mysql - 如何从我想要的行和基于某一列的“下一个”行中获取属性？

Question

我有一张这样的桌子：

startyearmonthday| id
20130901         |  1
20131004         |  2
20130920         |  3
20131105         |  4
20131009         |  5

我想写一个查询，我可以返回这样的表：

startyearmonthday| id  | endyearmonthday
20130901         |  1  | 20130920
20130920         |  3  | 20131004
20131004         |  2  | 20131009
20131009         |  5  | 20131105
20131105         |  4  | null

所以我希望结束日期基于当前开始日期之后的下一个最早开始日期。我想涉及某种加入，但我无法弄清楚......

Answer 1

试试这个（假设没有重复的行）：

select a.*, b.startyearmonthday as endyearmonthday
from table_name a
left join table_name b
on b.startyearmonthday > a.startyearmonthday and not exists(select startyearmonthday from table_name c where a.startyearmonthday < c.startyearmonthday and c.startyearmonthday < b.startyearmonthday)

Answer 2

我倾向于使用相关的子查询来做到这一点：

select t.*,
       (select startyearmonthday
        from t t2
        where t2.startyearmonthday > t.startyearmonthday
        order by t2.startyearmonthday
        limit 1
       ) as endyearmonthday
from t;

与您之前的问题一样，这将在索引上运行得非常快t(startyearmonthday)。