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SQL查询初学者指南读书笔记(五)集合操作与多表查询介绍

2015-06-03

PART III:Thinking in Sets CHAPTER7 Thinking in Sets The three mostcommon set operations are as follows Intersection Difference Union 在SQL中相应的关键词分别是 Intersection



PART III:Thinking in Sets
CHAPTER7 Thinking in Sets
The three mostcommon set operations are as follows.
Intersection
Difference
Union

在SQL中相应的关键词分别是

Intersection
Except
Union

实际数据库实现一般支持以下相应的数据库集合操作

INNER JOIN
OUTER JOIN
UNION JOIN

不过其区别是前者集合操作涉及表中所有列的值,而JOINs则只涉及到表中指定的列值.

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