The Relational Algebra的意思|示意

SQL, which is a structured query language, has been an international standard language of relational database. This paper shows the corresponding relations between algebra of relations and SQL.

SQL 是一种结构化的查询语言，已成为关系数据库的国际标准语言。

Aiming at how the DBMS query optimizer to generate the smallest cost query plan, optimization rules of the relational algebra expression are given.

针对DBMS查询优化器如何生成成本最小的查询计划问题，给出关系代数表达式的优化规则。

Similarly, based on the medium set theory MS, the medium relational algebra can extend the capability of relational algebra.

同样地，中介关系代数以中介集合论MS为基础，扩充了关系代数的功能。

Is also a great introduction to this topic and shows the motivation and theory behind the "relational algebra" in ActiveRecord 3.

也是一个关于此话题的很好的介绍，解释了ActiveRecord 3中的“关系代数”背后的的动机和理论。

This theoretical model allows, for example, that relational algebra operations to be replaced by more efficient equivalent operations whereas not interfere with the result.

例如，这种理论模型允许用更有效的等价操作来代替关系代数操作同时不影响结果。

Another benefit of the move to DB2 9 is the hybrid storage engine and a query optimizer that "understands" XML (mapping to relational algebra for queries involving XML).

迁移到DB 2 9的另一个好处是，混合型存储引擎和查询优化器“理解”X ML，可以把涉及XML的查询映射为关系语法。