ST_Z — Returns the Z coordinate of a Point.
float ST_Z(
geometry a_point)
;
Return the Z coordinate of the point, or NULL if not available. Input must be a point.
To get the minimum and maximum Z value of geometry coordinates use the functions ST_ZMin and ST_ZMax. |
This method implements the SQL/MM specification.
This function supports 3d and will not drop the z-index.
SELECT ST_Z(ST_GeomFromEWKT('POINT(1 2 3 4)')); st_z ------ 3 (1 row)