摘要： RAYMOND REITER在中给出了一个带空值的关系数据库的查询求解算法,这个算法是正确的,但并不能保证其完备性。本文给出了一个测试REITER算法在某一数据库的求解过程中是否保持其完备性的算法,由此可知,通过REITER算法求得的解是完全解还是部分解。此外,本文还给出了一个与REITER算法等价的但却更高效的查询求解算法。

Abstract: In [1], Raymond Reiter proposed a method for evaluating queries in relational databases with null values which represent existing but unknown individuals. The method is sound but not complete in general. In this paper, an algorithm to test the completion for query evaluation of REITER algorithm has been developed, by which we can know whether the answer given by REITER algorithm is complete or partial. In addition, a more efficient algorithm equivalent to REITER algorithm is also given.