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stackoverflow自己有很多办理方案,其方针是行使自动增量字段或时刻戳读取表的最后n行：譬喻,以下查询以降序从名为tab的表中获取最后10个记录名为id的字段值,它是表中的自动增量字段：
Select * from tab order by id desc limit 10
我的题目是：是否有任何更换要领,而无需得到自动增量字段或时刻戳来完成使命以得到沟通的输出？
提醒：提出这个题目的念头来自以下究竟：我们将记录存储到表中,并在行使简朴查询查询数据库时未指定任何尺度,譬喻：
Select * from tab
然后输出的次序与插入表中的记录次序沟通.那么有没有步伐凭证与输入数据库相反的次序获取记录？
最佳谜底
In the SQL world,order is not an inherent property of a set of data.
Thus,you get no guarantees from your RDBMS that your data will come
back in a certain order — or even in a consistent order — unless you
query your data with an ORDER BY clause.
因此,假如您没有按某些ID或某些列排序的数据,则无法按照其排序跟踪数据.因此无法担保MYSQL怎样存储数据,因此您无法得到最后n笔记录.
您还可以查察此article：
Caveats
Ordering of Rows
In the absence of ORDER BY,records may be returned in a different
order than the previous MEMORY implementation.
This is not a bug. Any application relying on a specific order without
an ORDER BY clause may deliver unexpected results. A specific order
without ORDER BY is a side effect of a storage engine and query
optimizer implementation which may and will change between minor MySQL
releases.
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