ST_ZMax
ST_ZMax returns the maximum z
coordinate of an input geometry.
Syntax
ST_ZMax(geom)
Arguments
- geom
-
A value of data type
GEOMETRY
or an expression that evaluates to aGEOMETRY
type.
Return type
DOUBLE PRECISION
value of the maximum z
coordinate.
If geom is empty, then null is returned.
If geom is null, then null is returned.
If geom is a 2D or 3DM geometry, then null is returned.
Examples
The following SQL returns the largest z
coordinate of a linestring in a 3DZ geometry.
SELECT ST_ZMax(ST_GeomFromEWKT('LINESTRING Z (0 1 2, 3 4 5, 6 7 8)'));
st_zmax
-----------
8
The following SQL returns the largest z
coordinate of a linestring in a 4D geometry.
SELECT ST_ZMax(ST_GeomFromEWKT('LINESTRING ZM (0 1 2 3, 4 5 6 7, 8 9 10 11)'));
st_zmax
-----------
10