SQL复杂查询到关系代数查询等价性的转换算法

An Algorithm for Equivalence of Translating SQL Into Relational Algebra

本文引入一种选择操作OSL,提出将SOL 查询转换为关系代数查询的新的转换算法。文中把SOL 查询分为两类:基本查询和扩展查询。算法的基本思想是把扩展查询先转换为基本查询,再将基本查询转换为关系代数查询,以消除复杂查询转换结果与原查询的不等价性。

This paper introduces a selection operation OSL and proposes an algorithm for translating SOL into relational algebra.The fundamental of the algorithm is that expansive query is translated into basic query,and basic query is translated into relational algebra query.