CTE 和子查询的区别? [英] Difference between CTE and SubQuery?

问题描述

从这篇文章 如何在以下程序?

答案有两种版本，一种使用子查询，另一种使用CTE来解决相同的问题.

There are two versions of answers where one uses a sub-query and the other uses a CTE to solve the same problem.

那么，与子查询"相比，使用 CTE(通用表表达式) 有什么优势(因此，可读性 查询实际在做什么)

Now then, what is the advantage of using a CTE (Common Table Expression) over a 'sub-query`(thus, more readable what the query is actually doing)

使用 CTE 而不是 sub-select 的唯一优点是我实际上可以 name sub-query.当 CTE 用作简单(非递归)CTE 时，这两者之间是否还有其他区别?

The only advantage of using a CTE over sub-select is that I can actually name the sub-query. Are there any other differences between those two when a CTE is used as a simple (non-recursive) CTE?

推荐答案

在子查询 vs simple(非递归)CTE 版本中，它们可能非常相似.您必须使用分析器和实际执行计划来发现任何差异，这将取决于您的设置(因此我们无法完整地告诉您答案).

In the sub-query vs simple (non-recursive) CTE versions, they are probably very similar. You would have to use the profiler and actual execution plan to spot any differences, and that would be specific to your setup (so we can't tell you the answer in full).

在一般中；CTE 可以递归使用；子查询不能.这使得它们特别适合树结构.

In general; A CTE can be used recursively; a sub-query cannot. This makes them especially well suited to tree structures.

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