ST_SetPoint — 将线串的点替换为给定点。
geometry ST_SetPoint(
geometry linestring, integer zerobasedposition, geometry point)
;
将线串的点N替换为给定点。指数是以0为基数的。负指数被倒数计算,因此-1是最后一个点。当一个顶点移动时尝试保持关节关系时,这在触发器中特别有用。
可用性:1.1.0
更新2.3.0:负面索引
This function supports 3d and will not drop the z-index.
--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)