如何计算一组结果中两行点之间的距离？答案

【问题标题】：How can I calculate the distance between 2 rows' points in a set of results?如何计算一组结果中两行点之间的距离？
【发布时间】：2013-11-10 13:41:45
【问题描述】：

我有一个查询，它采用 LINESTRING 并将其转换为 POINTS 结果集。

我想不通的是如何在这个结果集中找到 2 个特定行点之间的距离。

这是我目前所拥有的：

DECLARE @GeographyToConvert geography
SET     @GeographyToConvert = geography::STGeomFromText('LINESTRING (26.6434033 -81.7097817, 26.6435367 -81.709785, 26.6435783 -81.7098033, 26.6436067 -81.709825, 26.6435883 -81.709875, 26.64356 -81.7100417, 26.6434417 -81.710125, 26.6433167 -81.7101467, 26.643195 -81.7101033, 26.6431533 -81.7099517, 26.643175 -81.7097867, 26.643165 -81.7097917, 26.6431633 -81.7097367, 26.6431583 -81.7097083)',4326);
WITH GeographyPoints(N, Point) AS  
( 
   SELECT 1,  @GeographyToConvert.STPointN(1)
   UNION ALL
   SELECT N + 1, @GeographyToConvert.STPointN(N + 1)
   FROM GeographyPoints GP
   WHERE N < @GeographyToConvert.STNumPoints() 
)

SELECT N,Point.STBuffer(0.25) as point, Point.STAsText() FROM GeographyPoints

例如，如何比较 N=10 和 N=11 之间的距离？

这是我正在尝试的，但它不起作用：

Declare @Point1 geography;
Declare @Point2 geography;

DECLARE @GeographyToConvert geography
--SET     @GeometryToConvert = (select top 1 geotrack from dbo.SYNCTESTING2 where geotrack is not null);
SET     @GeographyToConvert = geography::STGeomFromText('LINESTRING (26.6434033 -81.7097817, 26.6435367 -81.709785, 26.6435783 -81.7098033, 26.6436067 -81.709825, 26.6435883 -81.709875, 26.64356 -81.7100417, 26.6434417 -81.710125, 26.6433167 -81.7101467, 26.643195 -81.7101033, 26.6431533 -81.7099517, 26.643175 -81.7097867, 26.643165 -81.7097917, 26.6431633 -81.7097367, 26.6431583 -81.7097083)',4326);
WITH GeographyPoints(N, Point) AS  
( 
   SELECT 1,  @GeographyToConvert.STPointN(1)
   UNION ALL
   SELECT N + 1, @GeographyToConvert.STPointN(N + 1)
   FROM GeographyPoints GP
   WHERE N < @GeographyToConvert.STNumPoints() 
)


SELECT N,Point.STBuffer(0.25) as point, Point.STAsText() FROM GeographyPoints

select @Point1 = Point FROM GeometryPoints where N = 10;

select @Point2 = Point FROM GeometryPoints where N = 11

select @Point1.STDistance(@Point2) as [Distance in Meters]

【问题讨论】：

分析函数可以帮助你。 technet.microsoft.com/en-us/library/hh213234.aspx 它允许您获取下一个或上一个值。

标签： sql tsql sql-server-2008-r2 common-table-expression spatial

【解决方案1】：

替换

SELECT N,Point.STBuffer(0.25) as point, Point.STAsText() FROM GeographyPoints

与

SELECT * INTO #GeographyPoints FROM GeographyPoints

DECLARE @N1 INT = 10
DECLARE @N2 INT = 11

SELECT (SELECT Point FROM #GeographyPoints WHERE N=@N1).STDistance(
            (SELECT Point FROM #GeographyPoints WHERE N=@N2))

DROP TABLE #GeographyPoints

只需根据需要更改 @N1 和 @N2 的值

【讨论】：

这正是我想做的！我用这样的东西编辑了我的初始帖子，但语法不正确。你的男人！！！
CTE 有一个技巧，您只能访问该表一次，因此在这种情况下，您必须将值存储到临时表中，然后将它们从临时表中拉出。 stackoverflow.com/questions/1590994/…

【解决方案2】：

这就是你要找的吗？到前一点的距离？

DECLARE @GeographyToConvert geography
SET     @GeographyToConvert = geography::STGeomFromText('LINESTRING (26.6434033 -81.7097817, 26.6435367 -81.709785, 26.6435783 -81.7098033, 26.6436067 -81.709825, 26.6435883 -81.709875, 26.64356 -81.7100417, 26.6434417 -81.710125, 26.6433167 -81.7101467, 26.643195 -81.7101033, 26.6431533 -81.7099517, 26.643175 -81.7097867, 26.643165 -81.7097917, 26.6431633 -81.7097367, 26.6431583 -81.7097083)',4326);
WITH GeographyPoints(N, Point, PreviousPoint, DistanceFromPrevious) AS  
( 
   SELECT 1,  @GeographyToConvert.STPointN(1), CAST(NULL AS GEOGRAPHY), CAST(0 AS Float)
   UNION ALL
   SELECT N + 1, @GeographyToConvert.STPointN(N + 1)
            , @GeographyToConvert.STPointN(N)
            , @GeographyToConvert.STPointN(N).STDistance(@GeographyToConvert.STPointN(N + 1))
   FROM GeographyPoints GP
   WHERE N < @GeographyToConvert.STNumPoints() 
)

SELECT N,Point.STBuffer(0.25) as point, Point.STAsText(), PreviousPoint, DistanceFromPrevious FROM GeographyPoints

【讨论】：

我希望能够手动选择从哪两个点计算距离。使用 N 列来确定我想要的 2。差不多了