ST_HasZ — Checks if a geometry has a Z dimension.
boolean ST_HasZ(geometry geom);
Checks if the input geometry has a Z dimension and returns a boolean value. If the geometry has a Z dimension, it returns true; otherwise, it returns false.
Geometry objects with a Z dimension typically represent three-dimensional (3D) geometries, while those without it are two-dimensional (2D) geometries.
This function is useful for determining if a geometry has elevation or height information.
Availability: 3.5.0
            
 Questa funzione supporta il 3d e non distrugge gli z-index. 
            
 Questa funzione supporta le coordinate M. 
SELECT ST_HasZ(ST_GeomFromText('POINT(1 2 3)'));
 --result
 true
        SELECT ST_HasZ(ST_GeomFromText('LINESTRING(0 0, 1 1)'));
 --result
 false