关键词: Query optimization 、 Database 、 View 、 Computer science 、 Query language 、 RDF query language 、 Query by Example 、 Database theory 、 Programming language 、 Database design 、 Data manipulation language
摘要: The user's conceptual model of a database system for geometric data should be simple and precise: easy to learn understand, with clearly defined semantics, expressive: allow express ease all desired query manipulation tasks, efficiently implementable.