地理空间数据类型 geography 是作为 SQL Server 中的 .NET 公共语言运行时 (CLR) 数据类型实现的。 此类型表示圆形地球坐标系中的数据。 geography 数据类型存储椭球体（圆形地球）数据，如 GPS 纬度和经度坐标SQL Server 。 SQL Server 支持 geography 空间数据类型的一组方法。 这些方法包括开放地理空间信息联盟 (OGC) 标准和对该标准的一组 Microsoft 扩展所定义的 geography 方法。
--总表面积
SELECT geography::STGeomFromText('POLYGON((-122.358 47.653, -122.348 47.649, -122.348 47.658, -122.358 47.658, -122.358 47.653))', 4326).STArea()
--二进制（WKB）表示形式
SELECT geography::STGeomFromText('LINESTRING( -122.360 47.656, -122.343 47.656)', 4326).STAsBinary()
--WKT表示形式
SELECT geography::STGeomFromText('LINESTRING(-122.360 47.656, -122.343 47.656)', 4326).STAsText()
--缓冲区
SELECT geography::STGeomFromText('LINESTRING(-122.360 47.656, -122.343 47.656)', 4326).STBuffer(1)
--返回指定的曲线
SELECT geography::STGeomFromText('COMPOUNDCURVE (CIRCULARSTRING (-122.358 47.653, -122.348 47.649, -122.348 47.658), CIRCULARSTRING(-122.348 47.658, -122.358 47.658, -122.358 47.653))',4326).STCurveN(2)
--圆弧线段的多边形近似值
SELECT geography::STGeomFromText('CIRCULARSTRING(-122.358 47.653, -122.348 47.649, -122.348 47.658, -122.358 47.658, -122.358 47.653)',4326).STCurveToLine()
--差集
SELECT geography::STGeomFromText('POLYGON((-122.358 47.653, -122.348 47.649, -122.348 47.658, -122.358 47.658, -122.358 47.653))', 4326).STDifference(geography::STGeomFromText('LINESTRING(-122.360 47.656, -122.343 47.656)', 4326))
--最大维度
SELECT geography::STGeomFromText('POLYGON((-122.358 47.653, -122.348 47.649, -122.348 47.658, -122.358 47.658, -122.358 47.653))', 4326).STDimension()
--是否不相联
SELECT geography::STGeomFromText('LINESTRING(-122.360 47.656, -122.343 47.656)', 4326).STDisjoint(geography::STGeomFromText('POINT( -122.343 47.656)', 4326))
--距离
SELECT geography::STGeomFromText('LINESTRING(-122.360 47.656, -122.343 47.656)', 4326).STDistance(geography::STGeomFromText('POINT(-122.34900 47.65100)', 4326))
--终点
SELECT geography::STGeomFromText('LINESTRING(-122.360 47.656, -122.343 47.656)', 4326).STEndPoint()
--判断是否相等
SELECT geography::STGeomFromText('GEOMETRYCOLLECTION(POLYGON((-122.368 47.658, -122.338 47.649, -122.338 47.658, -122.368 47.658, -122.368 47.658)), LINESTRING(-122.360 47.656, -122.343 47.656), POINT (-122.35 47.656))', 4326).STEquals(geography::STGeomFromText('POLYGON((-122.368 47.658, -122.338 47.649, -122.338 47.658, -122.368 47.658, -122.368 47.658))', 4326))
--查找GeometryCollection中第n个实例
SELECT geography::STGeomFromText('MULTIPOINT(-122.360 47.656, -122.343 47.656)', 4326).STGeometryN(2)
--类型
SELECT geometry::STGeomFromText('POLYGON((-122.358 47.653, -122.348 47.649, -122.348 47.658, -122.358 47.658, -122.358 47.653))', 4326).STGeometryType()
--交集
SELECT geography::STGeomFromText('POLYGON((-122.358 47.653, -122.348 47.649, -122.348 47.658, -122.358 47.658, -122.358 47.653))', 4326).STIntersection(geography::STGeomFromText('LINESTRING(-122.360 47.656, -122.343 47.656)', 4326))
--判断是否相交
SELECT geography::STGeomFromText('POLYGON((-122.358 47.653, -122.348 47.649, -122.348 47.658, -122.358 47.658, -122.358 47.653))', 4326).STIntersects(geography::STGeomFromText('LINESTRING(-122.360 47.656, -122.343 47.656)', 4326))
--判断是否闭合
SELECT geography::STGeomFromText('POLYGON((-122.358 47.653, -122.348 47.649, -122.348 47.658, -122.358 47.658, -122.358 47.653))', 4326).STIsClosed()
--判断是否为空
SELECT geography::STGeomFromText('POLYGON EMPTY', 4326).STIsEmpty()
--判断是否为有效geography格式
SELECT geography::STGeomFromText('LINESTRING(0 0, 2 2, 1 0)', 4326).STIsValid()
--边长总长度
SELECT geography::STGeomFromText('POLYGON((-122.358 47.653, -122.348 47.649, -122.348 47.658, -122.358 47.658, -122.358 47.653))', 4326).STLength()
--一维geography曲线数
SELECT geography::STGeomFromText('COMPOUNDCURVE(CIRCULARSTRING(-122.358 47.653, -122.348 47.649, -122.348 47.658, -122.358 47.658, -122.358 47.653))',4326).STNumCurves()
--geometry数量
SELECT geography::STGeomFromText('MULTIPOINT((-122.360 47.656), (-122.343 47.656))', 4326).STNumGeometries()
--点数量
SELECT geography::STGeomFromText('GEOMETRYCOLLECTION(CIRCULARSTRING(-122.358 47.653, -122.348 47.649, -122.348 47.658, -122.358 47.658, -122.358 47.653) ,CURVEPOLYGON(CIRCULARSTRING(-122.358 47.653, -122.348 47.649, -122.348 47.658, -122.358 47.658, -122.358 47.653)))', 4326).STNumPoints()
--指定点
SELECT geography::STGeomFromText('LINESTRING(-122.360 47.656, -122.343 47.656)', 4326).STPointN(2)
--空间参考
SELECT geography::STGeomFromText('LINESTRING(-122.360 47.656, -122.343 47.656)', 4326).STSrid
--起点
SELECT geography::STGeomFromText('LINESTRING(-122.360 47.656, -122.343 47.656)', 4326).STStartPoint()
--余集
SELECT geography::STGeomFromText('POLYGON((-122.358 47.653, -122.348 47.649, -122.348 47.658, -122.358 47.658, -122.358 47.653))', 4326).STSymDifference(geography::STGeomFromText('POLYGON((-122.351 47.656, -122.341 47.656, -122.341 47.661, -122.351 47.661, -122.351 47.656))', 4326))
--并集
SELECT geography::STGeomFromText('POLYGON((-122.358 47.653, -122.348 47.649, -122.348 47.658, -122.358 47.658, -122.358 47.653))', 4326).STUnion(geography::STGeomFromText('POLYGON((-122.351 47.656, -122.341 47.656, -122.341 47.661, -122.351 47.661, -122.351 47.656))', 4326))
官方资料：
https://docs.microsoft.com/zh-cn/previous-versions/sql/sql-server-2008/bb933960(v=sql.100)