Question

我是地图世界的新手，我正在尝试将SQL Server地理线列转换回它的纬度\经度点以在地图上绘制。

这条线正如此设置

Set @GeoPoly = geography::STGeomFromText('LINESTRING('+@Polyline+')',4326)

任何人都知道如何做到这一点？提前致谢

Answer 1

我很幸运：

DECLARE @g geography;
SET @g = geography::STLineFromText(
   'LINESTRING(-122.360 47.656, -122.343 47.656 )'
    , 4326
); 
SELECT @g.STPointN(1).ToString(), @g.STPointN(2).ToString();

Answer 2

你的LineString是否只包含一个连接两个点的直线段？如果是这样，您可以检索这些点的纬度和经度：

SELECT
  @GeoPoly.STStartPoint.Lat AS Start_Lat,
  @GeoPoly.STStartPoint.Long AS Start_Long,
  @GeoPoly.STEndPoint.Lat AS End_Lat,
  @GeoPoly.STEndPoint.Long AS End_Long;

如果您的LineString包含多个连接一系列点的线段，那么您可以使用ToString（）方法检索已知文本表示，然后通过在逗号上拆分将结果字符串解析为坐标对：

SELECT @GeoPoly.ToString()

结果将采用以下格式：LINESTRING（Lon1 Lat1，Lon2，Lat2，....，Lonn，Latn）

Answer 3

您可以通过组合STasText（），STRING_SPLIT（），CROSS APPLY和STRING_AGG（）在查询中实现此目的。这是查询示例：

WITH Links AS (
    SELECT Id, REPLACE(REPLACE(PosList.STAsText(), 'LINESTRING (', ''), ')', '') as points_string
    FROM LinkSequenceProjections
    WHERE ImportFileId = 1
    AND Id < 5
)
, Points AS (
    SELECT Id, ltrim(value) as point_string, row_number() OVER (PARTITION BY Id ORDER By Id) as Nr
    FROM Links
    CROSS APPLY STRING_SPLIT(points_string, ',')
)
, Coords AS (
    SELECT Id, Nr, CAST(value AS [varchar](max)) AS coord
    FROM Points
    CROSS APPLY STRING_SPLIT(point_string, ' ')
)
, GroupedByNr AS (
    SELECT Id, Nr, MIN(coord) AS Lon, MAX(coord) AS Lat
    FROM Coords
    GROUP BY Id, Nr
)
, GroupedById AS (
    SELECT Id, 'LINSESTRING (' + STRING_AGG(Lon + ' ' + Lat, ', ') WITHIN GROUP (ORDER BY Nr) + ')' as wkt2
    FROM GroupedByNr
    GROUP BY Id
)
SELECT Id, geography::STGeomFromText(wkt2, 4326) AS PosList2
FROM GroupedById

如何从SQL Server 2008地理线获取Latitude Longitude？

3 个答案: