基于扩展NXD的GML空间数据库数据查询系统

DATA QUERY SYSTEM OF GML SPATIAL DATABASE BASED ON EXPANDED NXD

目前,地理标识语言(GML)已成为事实上的空间数据编码、传输、存储和发布的国际标准语言。然而,传统的查询语言(例如SQL及扩展的SQL)不适合GML文档的直接查询和更新。此外,即使能把可扩展标识语言(XML)有效地应用于GML文档,也不能确保查询结果正确,譬如,W3C的XQuery是一种强大的XML标准查询语言,但它也不支持空间要素(GML文档的重要组成部分)的查询和更新操作。在研究了基于扩展NXD(原生可扩展标识语言数据库)的GML空间数据库特征的基础上,提出了XQuery查询的空间扩展和XQuery语法的扩展,并在一定程度上实现了基于扩展NXD的GML空间数据库的数据查询。

Currently, Geography Markup Language（GML） has become actually the international standard language for spatial data encoding, transmission, storage and release. Traditional query languages such as SQL and SQL extension , however, are not suitable for direct inquiry and updating of GML documents. Even the effective approaches working well with eXtensible Markup Language （XML） can not guarantee good results when applied to GML documents, for example, the W3 C XQuery is a powerful standard query language for XML, but it does not support querying spatial features which includes the most important components in GML documents. We put forward the expansions of Inquiry of XQuery and space XQuery syntax, and to some extent, realize the data query of GML spatial database based on the expansion of Native XML Database （NXD）.