Application of the active layer as a query tool in the embedded MapX

This Paper studies the principles of query functions on the digital map which embedded in Delphi7 through MapX component and provides a map query technology which takes the active layer as a query tool in the MapX. The map data in this paper is from 2002-2003 digital China map, the technologies involved are based on Station Query System which has been actually implemented in the Radio Short-wave Monitoring Network.