Spatial database has become one of the dominating techniques tomanage spatialdata in geographical information systems
and geographic structured query language (GSQL) is the key issue ofspatialdatabase design and implementation. Atpresent
GSQL for vector data has been widely studied. However
when considering the raster data
little researchwas made for their specifications on visiting and operationa.l Based on OpenGIS○R
a GSQL extension named GSQL2R supporting raster data is discussed in this paper. At first
some abstractdata types (ADTs)
includingPixe
l RasterRegion and RasterCoverage
are defined. The relationships between Pixel/RasterRegion and RasterRegion/RasterCoverage are part/whole. In these definitions
data objects and operations for each ADT are described in a formalized way. Then
GSQL2R syntax and some instances are presented. The GSQL2R description includes three parts
.i e. data definition language (DDL)
data table schema and data manipulation language (DML). The example indicates that GSQL2R provides an efficient and integrated way for raster data access and operation.