join和subquires之间的区别 [英] Difference between join and subquires

问题描述

1）。sq服务器中join和subquries之间的差异？

2）。join和subquires会给出相同的reslut设置吗？

如果可能的话告诉我怎么做？

1).Difference between join and subquries in sq server?
2).join and subquires will give same reslut set?
if possible tell me how?

推荐答案

您可以在网上找到大量讨论。看看这两个：

1. 加入和子查询 [ ^ ]

2. SQL联接和子查询 [ ^ ]

You can find plenty of discussions on the web. Check out these two:
1. join-and-sub-query[^]
2. SQL Joins and Subqueries[^]

你应该考虑购买一本关于SQL的书，或者使用谷歌。您的问题是基本的，顶级的，并且很难在论坛回复中完全回答。



简而言之，子查询意味着必须为每个查询运行相同的查询主查询中的行。连接运行一次然后加入。它更快，更高效。总是有很多方法可以在SQL中获得相同的结果，你所谈论的是一个更好的过程问题，而不是不同的结果。

You should consider buying a book on SQL, or using Google. Your question is basic, top level, and very difficult to answer fully in a forum reply.

In short, a sub query means the same query has to run for every row in the main query. A join runs once and then joins. It's faster, and more efficient. There's always a lot of ways to get the same result in SQL, what you're talking about is a question of better processes, not different results.

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