ST_Force3DM-ApsaraDB RDS(RDS)-阿里云帮助中心

Converts a geometry object to a 3DM geometry by adding M coordinates. Z coordinates, if present, are removed from the output.

Syntax

geometry ST_Force3DM(geometry geomA)

Parameter	Description
geomA	The input geometry object.

If the input geometry has no M coordinates, the M coordinate of each point in the output is set to 0.
If the input geometry has Z coordinates, the Z coordinates are removed from the output.
Supports circular strings and curves.

Input with no M or Z coordinates

SELECT ST_AsEWKT(ST_Force3DM(ST_GeomFromEWKT('POINT(1 2)')));

Output:

   st_asewkt
---------------
 POINTM(1 2 0)
(1 row)

Input with Z coordinates (Z is removed)

SELECT ST_AsEWKT(ST_Force3DM(ST_GeomFromEWKT('POINT(1 2 3)')));

Output:

   st_asewkt
---------------
 POINTM(1 2 0)
(1 row)