是连接和子查询是彼此不同的 [英] is join and subquery are different to each other

问题描述

是连接和子查询相同或不同。建议给我一些阅读...

is join and sub-query are same or different. suggest me some readings for it...

推荐答案

阅读本文

子查询，联接和联盟 [ ^ ]

SubQuery：嵌套在 SELECT 语句中的查询称为子查询并且是复杂的 join 语句的替代方法。

子查询组合来自多个表的数据并返回插入到主查询的WHERE条件中的结果。

子查询始终括在括号内并返回一列。子查询也可以称为内部查询，主查询可以称为外部查询。



联接： SQL联接用于根据这些表中某些列之间的关系查询来自两个或多个表的数据。要了解更多信息，请查看以下内容：



SQL加入 [ ^ ]



与子查询相比，SQL连接速度更快。



希望它有所帮助：）

SubQuery: A query nested inside a SELECT statement is known as a subquery and is an alternative to complex join statements.
A subquery combines data from multiple tables and returns results that are inserted into the WHERE condition of the main query.
A subquery is always enclosed within parentheses and returns a column. A subquery can also be referred to as an inner query and the main query as an outer query.

Joins:SQL joins are used to query data from two or more tables, based on a relationship between certain columns in these tables.To learn more check this:

SQL Joins[^]

SQL joins are faster as compared to subqueries.

hope it helps :)

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