PostGIS
Synopsis
+geometry +ST_AddPoint(+`geometry `+linestring, geometry
point`)`;
+geometry +ST_AddPoint(+`geometry `+linestring, geometry
point, integer position = -1`)`;
Description
Adds a point to a LineString before the index `position (using a
0-based index). If the position` parameter is omitted or is -1 the
point is appended to the end of the LineString.
Availability: 1.1.0
This
function supports 3d and will not drop the z-index.
Examples
Add a point to the end of a 3D line
SELECT ST_AsEWKT(ST_AddPoint('LINESTRING(0 0 1, 1 1 1)', ST_MakePoint(1, 2, 3)));
st_asewkt
----------
LINESTRING(0 0 1,1 1 1,1 2 3)Guarantee all lines in a table are closed by adding the start point of each line to the end of the line only for those that are not closed.
UPDATE sometable
SET geom = ST_AddPoint(geom, ST_StartPoint(geom))
FROM sometable
WHERE ST_IsClosed(geom) = false;