描述

返回几何图形的坐标尺寸。PostGIS支持2-(x，y)、3-(x，y，z)或2D测量-x，y，m和4-3D测量空间x，y，z，m

This function supports 3d and will not drop the z-index.

示例

SELECT ST_NDims(ST_GeomFromText('POINT(1 1)')) As d2point,
        ST_NDims(ST_GeomFromEWKT('POINT(1 1 2)')) As d3point,
        ST_NDims(ST_GeomFromEWKT('POINTM(1 1 0.5)')) As d2pointm;

         d2point | d3point | d2pointm
---------+---------+----------
           2 |       3 |        3
                        

另请参阅

ST_CoordDim, ST_Dimension, ST_GeomFromEWKT