如何转移点的X和Y的值? [英] How could I transfer the value of point's X and Y?

问题描述

功能如下:

create or replace function point_to_M(x float,y float, i integer)
    returns float AS
    $$
    DECLARE
        geo geometry;
        geo1 geometry;
    begin
      select testo.geom into geo from testo where lineid=i;
      geo1=st_astext(st_line_interpolate_point(st_geometryN(geo,1),'point(x y)')');
      return st_X(geo1);
    end;
    $$
    language plpgsql;

当我输入SQL时:

when I input the SQL:

select point_to_M(80,0,0);

错误是:

ERROR:  invalid input syntax for type double precision: "point(x y)"
LINE 1: ...ext(st_line_interpolate_point(st_geometryN(geo,1),'point(x y...

所以我认为原因可能是参数没有转移到函数中，但是我不确定，所以有人有这个问题吗?你能告诉我解决方案吗?非常感谢.

So I think the reason maybe is that the paramater didn't transfer into the function, but I am not sure, so does anyone had this problem? Could you tell me the solution? Thanks very much.

推荐答案

只需将经纬度长点转换为点

Just convert lat long to point

create or replace function point_to_M(x float,y float, i integer)
    returns float AS
    $$
    DECLARE
        geo geometry;
        geo1 geometry;
    begin
      select testo.geom into geo from testo where lineid=i;
      geo1=st_astext(st_line_interpolate_point(st_geometryN(geo,1),st_makepoint(x y)));
      return st_X(geo1);
    end;
    $$
    language plpgsql;

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