ST_Z — Returns the Z coordinate of a Point.
float ST_Z(geometry a_point);
Devuelve la coordenada Z del punto, o NULL si no está disponible. La entrada debe ser un punto.
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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
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3
(1 row)