Selectivity Estimation is the base of spatial database query optimizer. 选择性估计是设计空间数据库查询优化器的基础。
Several examples are demonstrated to discuss the representing and querying ability of the new model and its database extension. 实例研究表明该模型及其数据库扩展很好表达时空现象并支持场数据的空间数据库管理和时空查询。