postgresql - 如何从线串postgis中获取积分

Question

我有线串 (0 0 , 2 4 , 5 5);

我需要以以下形式输出:

x (1st cell)   ||    y (2nd cell)

0              ||    0

2              ||    4

5              ||    5 

多边形也一样。怎么做？

Answer 1

您可以将 ST_X 和 ST_Y 与 ST_PointN 结合使用来获取单个点的 x 和 y，并使用 generate_series 为线串的每个点创建索引，例如，

with line as (select ST_GeomFromText('LINESTRING(0 0, 2 4, 5 5)') as geom)
    select ST_X(ST_PointN(geom,num)) as x, 
           ST_Y(ST_PointN(geom,num)) as y 
    from line,
(select generate_series(1, (select ST_NumPoints(geom) from line)) as num) 
    as series;