“选择"是否总是按主键排序?
针对所有 DBA 的一个基本简单问题.
A basic simple question for all of you DBA.
当我进行选择时，是否总是保证我的结果将按主键排序，还是应该使用order by"来指定它?
When I do a select, is it always guaranteed that my result will be ordered by the primary key, or should I specify it with an 'order by'?
我使用 Oracle 作为我的数据库.
I'm using Oracle as my DB.
推荐答案
不，如果您不使用order by"，则无法保证任何顺序.事实上，您不能保证从一个查询到下一个查询的顺序是相同的.请记住，SQL 以基于集合的方式处理数据.现在，一个或另一个数据库实现可能碰巧以某种方式提供排序，但您永远不应该依赖它.
No, if you do not use "order by" you are not guaranteed any ordering whatsoever. In fact, you are not guaranteed that the ordering from one query to the next will be the same. Remember that SQL is dealing with data in a set based fashion. Now, one database implementation or another may happen to provide orderings in a certain way but you should never rely on that.
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