Synopsis
float ST_Z(
geometry a_point)
;
描述
返回点的Z坐标,如果不可用,则返回值为空。输入必须是一个点。
This method implements the SQL/MM specification.
This function supports 3d and will not drop the z-index.
示例
SELECT ST_Z(ST_GeomFromEWKT('POINT(1 2 3 4)'));
st_z
------
3
(1 row)