書寫清潔整理PostgreSQL/PostGIS查詢

Question

此查詢創建一個市政總結報告，包括落在道路緩衝區內的所有受體計數，並按城市分組。

所以基本上輸出將

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; 

它運行完全正常，並創建與每個城市的正確計數的文件。我只是想知道這裏是否有多餘的代碼？它可以更清潔，不那麼凌亂？任何建議將不勝感激

Answer 1

正如我理解你的查詢，在每個子查詢中，你計數市鎮與其他表（學校，醫院等）加入記錄。我想你可以做所有的連接一次，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 

它看起來更清潔和可以理解的，我認爲它會產生相同的結果。