To support the retrieval, fusion and discovery of visual/multimedia information, a spatial query language for multiple data sources is needed. In this paper we describe a spatial query language interpreter which is based upon the a-operator sequence and in practice expressible in an SQL-like syntax. The algorithm for the a-query translator is explored in detail. The implementation of the algorithm including data structures, pseudo-codes and source codes in C is presented. Query examples handled successfully by the a-query implementation are also given out.