PostGIS 交叉点多几何

【问题标题】：PostGIS Intersection multiple geometryPostGIS 交叉点多几何
【发布时间】：2017-06-19 13:38:25
【问题描述】：

我有一个 postgis 多边形表 (zipcode1) 和两点表 (pm253, blockpop)。我想将多边形表与两个点表相交并计算每个点表有多少点，总结一些其他属性来计算比率。如您在此处看到的，我可以针对单个表执行此操作：

SELECT zipcode1.gid, count(*) as totpm, sum(pm) as totsum, sum(pm)/count(*) as res 
FROM pm253, zipcode1 
WHERE st_intersects(st_buffer(zipcode1.geom, 100),pm253.geom) 
GROUP BY zipcode1.gid

有什么建议吗？谢谢。

【问题讨论】：

标签： postgis intersect

【解决方案1】：

尝试联合；

SELECT 'zipcode1<->pm253' as tables, zipcode1.gid, count(*) as totpm, sum(pm) as totsum, sum(pm)/count(*) as res 
FROM pm253, zipcode1 
WHERE st_intersects(st_buffer(zipcode1.geom, 100),pm253.geom)  and zipcode1.geom&&pm253.geom -- to accelerate query
GROUP BY zipcode1.gid 

union

SELECT 'zipcode1<->blockpop' as tables, zipcode1.gid, count(*) as totpm, sum(pm) as totsum, sum(pm)/count(*) as res 
FROM blockpop, zipcode1 
WHERE st_intersects(st_buffer(zipcode1.geom, 100),blockpop.geom)  and zipcode1.geom && blockpop.geom -- to accelerate query
GROUP BY zipcode1.gid

【讨论】：