读取SQL数据库后，用mschart画多条折线，并可以通过键盘放大缩小折线，能实时显示数值-Read the SQL database, with more than MSChart painting line and can zoom through the keyboard line, real-time display numerical

完整介绍公交信息查询系统的开发过程 详细说明对地图的放大缩小-Full descr iption bus information system development process in detail zoom on the map