Examples of such emerging application domain is: Geographic Information Systems (GIS), Multimedia Information Systems, CAD / CAM, Time-Series Analysis, Medical Information Sstems, On-Line Analytical Processing (OLAP) and Data Mining. From the standpoint of the database, new techniques and tools therefore need to be developed toward increasing processing efficiency. This monograph discusses how spatial database management system aims to support queries that involve the characteristics of the underlying data space, and discuss the query processing techniques for nearest neighbor query.