如何從 SQL Server 2008 地理線獲取緯度經度？

Question

我是地圖世界的新手，我正在嘗試將 SQL Server 地理線列轉換回它的緯度\\經度點以在地圖上繪制。

這條線是這樣設置的

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

有人知道怎么做嗎？ 提前致謝

Answer 1

我很幸運：

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

您的 LineString 是否僅由一條連接兩點的直線段組成？ 如果是這樣，您可以將這些點的緯度和經度檢索為：

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 由連接一系列點的多個線段組成，那么您可以使用 ToString() 方法檢索 Well-Known Text 表示，然后通過逗號分割將結果字符串解析為坐標對：

SELECT @GeoPoly.ToString()

結果將采用以下格式：LINESTRING(Lon1 Lat1, Lon2, Lat2, .... , Lonn, Latn)

Answer 3

您可以通過組合 STasText()、STRING_SPLIT()、CROSS APPLY 和 STRING_AGG() 在查詢中實現這一點。 這是一個示例查詢：

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