Research And Implementation Of MAPGIS7.0 Spatial Query Language GSQL

The data in GIS can be categorized into spatial data and attribute data. The traditional GIS soft wares cannot solve the spatial data problem, so they use file or combining file and relation database to manage GIS dates. With the development of database technology, in order to use the dates of GIS to express realer world, in resent years, how to design the Object Oriented all relational database has became the study tendency of GIS spatial data model, which can fully use many fully-developed features applied in commercial database, such as memory buffer, speedy index, the data integrality, the coherence ensuring, combing control, security and recover mechanism and distributed process mechanism.However, whatever data storage mechanism you use, with the limit of the relation database itself, the query and analyzing on the relation database always are a hard work to do. Nowadays, there are some databases provide the supports to spatial datatype, but the manipulating approaches still are original and elemental. So ,as much as the present Geographic Information system, it is quite difficult to relatively systematically do the query based on spatial relation and the integrating query based on space and attribution. Therefore, many experts advise to use the spatial query language as the solution, and the spatial query language study have brought extensive attention.At the present time, the standard structural query language SQL in relation database has fully developed, and is well featured in problem oriented and being close to natural language, which have been universally acknowledged by this area. So, the spatial expanding query language based on standard SQL—GSQL, will be a tendency on managing and analyzing the spatial dates. The new generation GIS product MAPGIS7.0 is developed by WU HAN ZONDY CYBER-TECK CO., LTD. It is a network oriented super large-scale distributed geographic information system basal software platform, and it use the full relation database management and the object oriented design ideal to realize the concept uniform. The special query language is one of the important modules.The spatial query language GSQL designed and realizded in this paper is based on the OpenGIS criterion and SQL3 international standard, combined with the spatial data model of MAPGIS7.0, mainly use the compiler like lexical analysis, syntactical analysis and so on to interpret on input GSQL language scripts then a parsing tree is constructed, lately the MAPGIS7.0 client query...