如何计算SQL中两点沿线的距离

Question

我在 MSSQL 数据库中添加了代表 map.As、

中的一条路线的行

update route
  set locationArray=geography::STGeomFromText('LINESTRING(7.068419558716859 80.140939950943,7.070868430303301 80.14106869697571,7.072976578922316 80.14136910438538,7.074339417352194 80.14203429222107,7.07631978477513 80.14278531074524,7.078491790888004 80.14435172080994,7.078300143701023 80.14649748802185,7.078449202631107 80.14877200126648,7.076617903866453 80.15068173408508,7.074978246481405 80.15248417854309,7.074105179783337 80.15490889549255,7.0723803358444135 80.15643239021301)', 4326)
  where routeID=45;

现在我选择了直线上的两个点，然后我想计算这两条直线之间的距离（不是直接距离或位移），类似于图像。

我已经尝试了 STLength() 函数和 STDistance() 函数。但它们都提供直接距离。有人可以帮我用 TSQL 计算沿线的距离吗？

Answer 1

STLength (geometry Data Type)

Returns the total length of the elements in a geometry instance.

STLength (geography Data Type)

Returns the total length of the elements in a geography instance or the geography instances within a GeometryCollection.

我计算了Excel中每个段SQRT(X*X + Y*Y)的简单长度之和，并与SQL服务器进行了比较。对于 geometry 类型，Excel 给出了与 STLength 相同的结果。 STLength 不 计算从起点到终点的距离，它计算每个段的长度，然后按预期将它们相加。

DECLARE @G1 geometry  = geometry::STGeomFromText ('LINESTRING(7.068419558716859 80.140939950943,7.070868430303301 80.14106869697571,7.072976578922316 80.14136910438538,7.074339417352194 80.14203429222107,7.07631978477513 80.14278531074524,7.078491790888004 80.14435172080994,7.078300143701023 80.14649748802185,7.078449202631107 80.14877200126648,7.076617903866453 80.15068173408508,7.074978246481405 80.15248417854309,7.074105179783337 80.15490889549255,7.0723803358444135 80.15643239021301)', 4326);
DECLARE @G2 geography = geography::STGeomFromText('LINESTRING(7.068419558716859 80.140939950943,7.070868430303301 80.14106869697571,7.072976578922316 80.14136910438538,7.074339417352194 80.14203429222107,7.07631978477513 80.14278531074524,7.078491790888004 80.14435172080994,7.078300143701023 80.14649748802185,7.078449202631107 80.14877200126648,7.076617903866453 80.15068173408508,7.074978246481405 80.15248417854309,7.074105179783337 80.15490889549255,7.0723803358444135 80.15643239021301)', 4326);

SELECT @G1.STLength() AS LGeometry, @G2.STLength() AS LGeography;

结果

LGeometry             LGeography
0.0252888043080671    1809.85271737151

所以，STLength 工作正常，请检查您的代码。检查您使用的类型是否正确（geometry vs geography）。