ST_ZMin

ST_ZMin returns the minimum z coordinate of an input geometry.

Syntax

ST_ZMin(geom)

Arguments

Return type

DOUBLE PRECISION value of the minimum 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 smallest z coordinate of a linestring in a 3DZ geometry.

SELECT ST_ZMin(ST_GeomFromEWKT('LINESTRING Z (0 1 2, 3 4 5, 6 7 8)'));

st_zmin
-----------
  2               

The following SQL returns the smallest z coordinate of a linestring in a 4D geometry.

SELECT ST_ZMin(ST_GeomFromEWKT('LINESTRING ZM (0 1 2 3, 4 5 6 7, 8 9 10 11)'));

st_zmin
-----------
  2