描述

以給定的點取代線串的第 N 個點。索引是從 0 開始的。負索引則從後往前算，因此 -1 是最後一個點。當試圖在一個頂點移動時保持關節的關係時，這在觸發器中特別有用。

可用性：1.1.0

更新於 2.3.0：負索引

此函數支援 3D，並且不會捨棄 z 索引。

範例

--Change first point in line string from -1 3 to -1 1
SELECT ST_AsText(ST_SetPoint('LINESTRING(-1 2,-1 3)', 0, 'POINT(-1 1)'));
	   st_astext
-----------------------
 LINESTRING(-1 1,-1 3)

---Change last point in a line string (lets play with 3d linestring this time)
SELECT ST_AsEWKT(ST_SetPoint(foo.geom, ST_NumPoints(foo.geom) - 1, ST_GeomFromEWKT('POINT(-1 1 3)')))
FROM (SELECT ST_GeomFromEWKT('LINESTRING(-1 2 3,-1 3 4, 5 6 7)') As geom) As foo;
	   st_asewkt
-----------------------
LINESTRING(-1 2 3,-1 3 4,-1 1 3)

SELECT ST_AsText(ST_SetPoint(g, -3, p))
FROM ST_GEomFromText('LINESTRING(0 0, 1 1, 2 2, 3 3, 4 4)') AS g
	, ST_PointN(g,1) as p;
	   st_astext
-----------------------
LINESTRING(0 0,1 1,0 0,3 3,4 4)

			

參見

ST_AddPoint、ST_NPoints、ST_NumPoints、ST_PointN、ST_RemovePoint