地理空间数据库课堂练习二.docxVIP

/*课堂练习二*//*1.查找本数据库中所有的空间表*/select f_table_namefrom geometry_columns;/*2.查找streams表的空间参考系的授权*/select s.auth-sridfrom spatial_ref_sys s,geometry_columns gwhere g.f_table_name=streams and s.srid=g.srid;/*3.获得75号路的几何类型*/select st_geometrytype(centerlines)from divided_routes where name=路75;/*4.获得鹅岛的WKT表示*/select st_astext(boundary)from islandwhere name=鹅岛;/*5.判断名为路5，别名为“主街”的路段的几何属性是否为空*/select st_isempty(centerline)from road_segmentswhere name=路5 AND aliases = 主街;/*6.蓝湖的几何结构是否简单的*/select st_issimple(shore)from lakewhere name=蓝湖;/*7.获得鹅岛的边界*/select st_astext(st_boundary(boundary))from islandwhere name = 鹅岛;/*8.获得鹅岛的MBR边界*/select st_astext(st_envelope(boundary))from islandwhere name=鹅岛;/*9.获得卡姆桥的x，y坐标*/select st_x(position),st_Y(position)from bridgeswhere name=卡姆桥;/*10.获得102路段的起点和终点*/select st_astext(st_startpoint(centerline)),st_astext(st_endpoint(centerline))from road_segmentswhere fid=102;/*11.判断鹅岛的MBR边界是否闭合*/select st_isclosed(st_boundary(boundary))from islandwhere name=鹅岛;/*12.获得106路段的长度*/select st_length(centerline)from road_segmentswhere fid=106;/*13.获得102路段中点的数目*/select st_numpoints(centerline)from road_segmentswhere fid=102;/*14.获得102路段中点的第一个点*/select st_astext(st_pointn(centerline,1))from road_segmentswhere fid=102;/*15.获得鹅岛的质心*/select st_astext(st_centroid(boundary))from islandwhere name=鹅岛;/*16.判断PointOnSurface函数返回鹅岛上的点是否在其边界内*/select st_contains(boundary,st_pointonsurface(boundary))from islandwhere name=鹅岛;/*17.获得鹅岛的面积*/select st_area(boundary)from islandwhere name=鹅岛;/*18.获得蓝湖内环的数目*/select st_numinteriorring(shore)from lakeswhere name=蓝湖;/*19.判断75号路的几何元素的数目*/select st_numgeometries(centerlines)from divided_routeswhere name=路75;/*20.获得75号路的第2个几何元素*/select st_astext(st_geometryN(centerlines,2))from divided_routeswhere name=路75;/*21.获得75号路的长度*/select st_length(centerline)from divided_routewhere name=路75;/*22.判断鹅岛是否与其WKT表示构造的同样几何结构是否相等*/select st_equals(boundary,st_polyfromtext(polygon((67 13,67 18,59 18,59 13,67 13)),101))from islandwhere name=鹅岛;/*23.判断75号路是否与