Question

此查询创建一个市政总结报告，其中包含道路缓冲区内的所有受体计数，并按市政当局分组。

基本上输出将是

munname    school   childcare  hospitals etc...
"mun1"         3         4        0 
"mun2"         1         0         9


select b.mun,b.county,q1.schools,q2.childcares,q3.hospitals,q4.nursinghomes,q5.infrastructure,q6.streamwmi,q7.streammi,q8.rez,b.geometry into roadreport
        from (select muntruck.munname as mun,muntruck.muncounty as county,mun.geom as geometry from muntruck,mun 
            where muntruck.munname = mun.mun and muntruck.muncounty = mun.county) as b 
            left join(select count(schools.gid) as schools,muntruck.munname as mun,muntruck.muncounty as county from muntruck,schools
                where st_intersects(muntruck.igeom,schools.geom) group by muntruck.muncounty,muntruck.munname) as q1
                    on b.mun = q1.mun and b.county = q1.county 
            left join(select count(childcare.gid) as childcares,muntruck.munname as mun,muntruck.muncounty as county from muntruck,childcare 
                where st_intersects(muntruck.igeom,childcare.geom) group by muntruck.muncounty,muntruck.munname) as q2 
                    on b.mun = q2.mun and b.county = q2.county 
            left join(select count(hospitals.gid) as hospitals, muntruck.munname as mun,muntruck.muncounty as county from muntruck,hospitals
                where st_intersects(muntruck.igeom,hospitals.geom) group by muntruck.muncounty,muntruck.munname) as q3 
                    on b.mun = q3.mun and b.county = q3.county
            left join(select count(nursinghomes.gid) as nursinghomes, muntruck.munname as mun,muntruck.muncounty as county from muntruck,nursinghomes
                where st_intersects(muntruck.igeom,nursinghomes.geom) group by muntruck.muncounty,muntruck.munname) as q4
                    on b.mun = q4.mun and b.county = q4.county
            left join(select count(infra.gid) as infrastructure,muntruck.munname as mun,muntruck.muncounty as county from muntruck,infra
                where st_intersects(muntruck.igeom,infra.ggeom) group by muntruck.muncounty,muntruck.munname) as q5
                    on b.mun = q5.mun and b.county = q5.county
            left join(select sum(st_length(geom))/5280 as streamwmi, muntruck.munname as mun,muntruck.muncounty as county from muntruck, streamsw
                where st_intersects(muntruck.igeom,streamsw.geom) group by muntruck.muncounty,muntruck.munname) as q6
                    on b.mun = q6.mun and b.county = q6.county
            left join(select sum(st_length(geom))/5280 as streammi, muntruck.munname as mun,muntruck.muncounty as county from muntruck,streams
                where st_intersects(muntruck.igeom,streams.geom) group by muntruck.muncounty,muntruck.munname) as q7
                    on b.mun = q7.mun and b.county = q7.county
            left join(select sum(popest*((ST_Area(residentialpopulation.geom)/43560)/acresnew)) as rez, muntruck.munname as mun,muntruck.muncounty as county from muntruck,residentialpopulation
                where st_intersects(muntruck.igeom,residentialpopulation.geom) group by muntruck.muncounty,muntruck.munname) as q8
                    on b.mun = q8.mun and b.county = q8.county;

它运行完全正常，并为每个城市创建一个具有正确计数的文件。我只是想知道这里是否有多余的代码？它可以更干净，更少杂乱吗？任何建议将不胜感激

Answer 1

根据我的理解你的查询，在每个子查询中，你都会计算与其他一些表（学校，医院等）相关的市政府的记录。我想你可以立刻做所有的连接，比如：

SELECT 
    muntruck.munname AS mun,
    muntruck.muncounty AS county,
    mun.geom as geometry,
    COUNT(schools.gid) AS schools,
    COUNT(childcare.gid) AS childcares,
    COUNT(hospitals.gid) AS hospitals
FROM muntruck
JOIN mun ON (muntruck.munname = mun.mun AND muntruck.muncounty = mun.county)
LEFT JOIN schools ON ST_Intersects(muntruck.igeom, schools.geom)
LEFT JOIN childcare ON ST_Intersects(muntruck.igeom, childcare.geom)
LEFT JOIN hospitals ON ST_Intersects(muntruck.igeom, hospitals.geom)
GROUP BY 
    muntruck.muncounty,
    muntruck.munname,
    mun.geom

它看起来更干净，更容易理解，我认为它会产生相同的效果。

写更干净整洁的PostgreSQL / PostGIS查询

1 个答案: