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该文根据面向对象数据库对带有广义限制条件的查询语句的优化策略,比较了采用结构化查询语言表达此类查询的两种表述方式的执行效率,并推荐了基于反半连接的SQL表述方式.“,”This paper compares the efficiency of two SQL blockswhich implement the queries with universal quantification. The comparison is based on the optimizing techniques applied in OODB. According to the analysis, we recommend the better method of implementation, which expresses the concept of anti-semijoin operation.