GeoSQL: 一种可视化空间扩展SQL查询语言

根据结构化查询语言ＳＱＬ的基本原理，设计了空间查询语言ＧｅｏＳＱＬ及其表达形式、界面设计和实现方法。ＧｅｏＳＱＬ的特色为：①采用子查询（ｓｕｂｑｕｅｒｙ） 重组ＦＲＯＭ 语句，使其符合一般空间操作的程序；②ＧｅｏＳＱＬ的界面设计融入了Ｉｃｏｎ、Ｌｉｓｔｂｏｘ 等可视化部件，易于查询文本的形成，且减少了语法错误。

GeoSQL:a Visual Spatial SQL

This paper presents an approach to designing a spatial query language called GeoSQL, by extending the standard database language SQL. A critical factor to the design is how to accommodate spatial operators in an appropriate structure, while conforming well to the basic principles of SQL. To achieve this, the FROM clause of SQL is restructured to contain spatial operators via a subquery so that the results of spatial operations can be easily fed into both the SELECT and WHERE clauses. This is a distinct characteristic of GeoSQL. The syntax and semantics of GeoSQL are described, and a set of examples for testing the expressiveness of the language are given. The interface of the language is also designed with the introduction of visual constructs (e.g., icons and ListBoxes) to aid the entry of query text. This distinguishes GeoSQL's interface from the previous extended SQLs, which formulate a query only by typing. An implementation of GeoSQL is also discussed.