如何将多个LineString行合并为一个行集合 [英] How to combine multiple LineString rows into a single row collection

问题描述

我正在使用SQL Server 2008和Geometry数据类型来存储从

I'm using SQL Server 2008 and the Geometry datatype to store a list of UK a roads, which I've imported from the Ordanance Survey STRATEGI data set.

每条道路分为多行，每行包含一行(由一个路段组成的Linestring).例如，A369由18条单独的线组成，如下图所示:

Each road is split into multiple rows, which each contain a single line (A Linestring made up of one segment). For instance the A369 is made up of 18 seperate lines, as shown in the image below:

我要执行的操作是收集包含道路部分的所有单独行，并创建一个新行，其中将所有组合的单独行作为一个线串保存.

What I'd like to do it collect all the seperate rows containing portions of a road and create a new row which holds all the combined individual lines as one linestring.

换句话说，运行代码SELECT * FROM Structure WHERE Name = 'A369'将仅返回一行，但仍会绘制上图所示的道路.

In other words running the code SELECT * FROM Structure WHERE Name = 'A369' would return only one row, but still drawn the road seen in the image above.

推荐答案

只需使用.STUnion

Just use .STUnion

BEGIN
-- create a test table
DECLARE @test TABLE(seg GEOMETRY);
INSERT INTO @test VALUES(geometry::STGeomFromText('LINESTRING (0 0, 50 100)', 0))
INSERT INTO @test VALUES(geometry::STGeomFromText('LINESTRING (50 100, 100 200)', 0))
INSERT INTO @test VALUES(geometry::STGeomFromText('LINESTRING (100 200, 150 300)', 0))
--SELECT seg.STAsText() FROM @test
DECLARE @geom GEOMETRY
SELECT @geom = (SELECT TOP 1 seg FROM @test)
-- union all the linestring points
SELECT @geom = @geom.STUnion([seg]) FROM @test
-- do what you want with the results
SELECT @geom
print(@geom.STAsText())
END

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