ST_Force4D-ApsaraDB RDS(RDS)-阿里云帮助中心

Converts any geometry to a 4D geometry (XYZM). If the input geometry is missing a Z or M coordinate, the missing value defaults to 0.

Syntax

geometry ST_Force4D(geometry geomA);

Parameter	Description
`geomA`	The input geometry.

If the input geometry has no Z or M coordinate, the missing coordinate is set to 0.
This function supports 3D objects and does not delete z coordinates.
Supports circular strings and curves.

3D geometry: Z is preserved, M coordinate is added

SELECT ST_AsEWKT(ST_Force4D(ST_GeomFromEWKT('POINT(1 2 3)')));

   st_asewkt
----------------
 POINT(1 2 3 0)
(1 row)