我有 PostgreSQL8.4+PostGIS。
我有一列中有一个带有线串几何形状的表格。我有这个线串的一个点,我想得到下一个点。为此,我想使用函数ST_NPoints和ST_PointN。为了使用它,我必须对所有点进行排序找到我的点,然后我会知道下一点是我需要的。
这是我的桌子:
-- Table: filedata
-- DROP TABLE filedata;
CREATE TABLE filedata
(
num serial NOT NULL,
id integer,
mydata character(25),
the_geom geometry,
CONSTRAINT filedata_pkey PRIMARY KEY (num)
)
WITH (
OIDS=FALSE
);
ALTER TABLE filedata OWNER TO postgres;
和示例线串:
"LINESTRING(60.7014631515719 56.8441322356241,60.7023117507097 56.8445673405349,60.702948200063 56.8447993944193,60.703902874093 56.8448574076656,60.706236521722 56.8447993944193,60.7094187684889 56.8449444273664,60.7121236782406 56.8450894597515,60.715571112238 56.8452925041466,60.718382096882 56.8454085290207,60.7204505572805 56.8453505166286,60.7222538304482 56.8450314468649,60.7246405155233 56.8444513130533,60.7260194891224 56.8440742212539,60.7260194891224 56.8440742212539,60.7260194891224 56.8440742212539,60.7260194891224 56.844045214035)"