SQL在递归查询和逻辑谓词上的扩充

THE EXTENSION OF RECURSIVE QUERY AND LOGICAL PREDICATE IN SQL

本文讨论了对ＳＱＬ语言的递归查询和逻辑谓词功能上的扩充方法。给出了递归查询的关系代数表达式，并就考虑路径的递归查询和不考虑路径的递归查询两方面对ＳＱＬ在句法和算法上，对ＳＱＬ中逻辑谓词扩充的理论、句法和算法进行了讨论。

In this paper, we discuss a method to add the function of recursive query and the concept of logic predicate to SoL. In the first part, we give the relation algebra expression of recursive query, and the discussion of syntax and algorithm of two kinds of recursive query: 1. Considering path; 2. Not considering path. In the second part, we give the theory, syntax and algorithm of adding logic predicate to SoL.