ST_Z returns the z coordinate of an input point.
Syntax
ST_Z(point)
Arguments
- point
-
A
POINTvalue of data typeGEOMETRY.
Return type
DOUBLE PRECISION value of the m coordinate.
If point is null, then null is returned.
If point is a 2D or 3DM point, then null is returned.
If point is the empty point, then null is returned.
If point is not a POINT, then an error is returned.
Examples
The following SQL returns the z coordinate of a point in a 3DZ geometry.
SELECT ST_Z(ST_GeomFromEWKT('POINT Z (1 2 3)'));
st_z
-----------
3
The following SQL returns the z coordinate of a point in a 4D geometry.
SELECT ST_Z(ST_GeomFromEWKT('POINT ZM (1 2 3 4)'));
st_z
-----------
3
