在几列之间显示最大值的列名称

Question

我有从表单中收集的数据。并具有“摆动”的数据，所以它看起来是这样的：

COUNTY  | denver | seattle | new_york | dallas | san fran 
-----------+---------+-----------+----------+----------+--------- 
ada  | 3  | 14  | 0  | 0  | 0  
slc  | 10  | 0   | 0  | 0  | 9  
canyon  | 0  | 5   | 0  | 0  | 0  
washington | 0  | 0   | 11  | 0  | 0  
bonner  | 0  | 0   | 0  | 2  | 0 

（这是用case语句来完成，交叉表是不允许我使用环境：cartodb）

我现在需要一个列用最大值列出CITY。例如：

COUNTY  | CITY  | denver | seattle | new_york | dallas | san fran 
-----------+----------+---------+-----------+----------+----------+--------- 
ada  | seattle | 3  | 14  | 0  | 0  | 0  
slc  | denver | 10  | 0   | 0  | 0  | 9  
canyon  | seattle | 0  | 5   | 0  | 0  | 0  
washington | new_york | 0  | 0   | 11  | 0  | 0  
bonner  | dallas | 0  | 0   | 0  | 2  | 0 

感谢您的回复。我想知道是否可以在一个查询中做到这一点。例如，下面是我用得到我上面的数据写入第一表例如查询，whick摆动数据：

SELECT counties.name, counties.state, counties.the_geom, 
count(case when fandom_survey_one.favorite_team = 'Arizona Cardinals' then 'ari' end)          ari, 
count(case when fandom_survey_one.favorite_team = 'Atlanta Falcons' then 'atl' end) atl, 
count(case when fandom_survey_one.favorite_team = 'Baltimore Ravens' then 'bal' end) bal, 
count(case when fandom_survey_one.favorite_team = 'Buffalo Bills' then 'buf' end) buf, 
count(case when fandom_survey_one.favorite_team = 'Carolina 
FROM fandom_survey_one, counties 
WHERE ST_Intersects(fandom_survey_one.the_geom, counties.the_geom) 
group by counties.name, counties.state, counties.the_geom 
order by counties.name, counties.state 

我不知道是否有以纳入戈登或者欧文提供这个答案的方式第一个查询可以在一个查询中完成。谢谢。

Answer 1

您可以用大case声明这样做：

select t.*, 
     (case when denver = greatest(denver, seattle, new_york, dallas, sanfran) then 'denver' 
      when seattle = greatest(denver, seattle, new_york, dallas, sanfran) then 'seattle' 
      when new_york = greatest(denver, seattle, new_york, dallas, sanfran) then 'new_york' 
      when dallas = greatest(denver, seattle, new_york, dallas, sanfran) then 'dallas' 
      when sanfran = greatest(denver, seattle, new_york, dallas, sanfran) then 'sanfran' 
     end) as City     
from table t; 

编辑：

我会在最后转动的结果。事情是这样的：

SELECT name, state, the_geom, 
     MAX(CASE WHEN seqnum = 1 THEN favorite_team END) as favorite_team, 
     MAX(CASE WHEN favorite_team = 'Arizona Cardinals' THEN cnt ELSE 0 END) as ari, 
     MAX(CASE WHEN favorite_team = 'Atlanta Falcons' THEN cnt ELSE 0 END) as atl, 
     MAX(CASE WHEN favorite_team = 'Baltimore Ravens' THEN cnt ELSE 0 END) as bal, 
     MAX(CASE WHEN favorite_team = 'Buffalo Bills' THEN cnt ELSE 0 END) as buf 
FROM (SELECT c.name, c.state, c.the_geom, s.favorite_team, count(*) as cnt, 
      ROW_NUMBER() OVER (PARTITION BY c.name, c.state, c.the_geom ORDER BY COUNT(*) desc) as seqnum 
     FROM fandom_survey_one s JOIN 
      counties c 
      ON ST_Intersects(s.the_geom, c.the_geom) 
     GROUP BY c.name, c.state, c.the_geom, s.favorite_team 
    ) c 
GROUP BY name, state, the_geom 
ORDER BY name, state 

Answer 2

这是一个"simple" or "switched" CASE声明，以避免重复代码的教科书范例。

SELECT CASE greatest(denver, seattle, new_york, dallas, "san fran") 
      WHEN denver  THEN 'denver' 
      WHEN seattle  THEN 'seattle' 
      WHEN new_york THEN 'new_york' 
      WHEN dallas  THEN 'dallas' 
      WHEN "san fran" THEN 'san fran' 
     END AS city, * 
FROM tbl; 

列表中的第一个（从左到右）在平行的情况下获胜。