描述

返回点的M坐标，如果不可用，则返回NULL。输入必须是点。

This method implements the OGC Simple Features Implementation Specification for SQL 1.1.

This method implements the SQL/MM specification.

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

示例

SELECT ST_M(ST_GeomFromEWKT('POINT(1 2 3 4)'));
 st_m
------
        4
(1 row)

                

另请参阅

ST_GeomFromEWKT , ST_X , ST_Y , ST_Z