Question

我有2张桌子，第一张叫做运动员，有列包括：

athlete_id，名字，姓氏，COUNTRY_ID

第二个表叫做奖牌和

有列：

年，体育，事件，athlete_id，奖章

这是运动员的一部分：

 athlete_id first_name last_name country_id
1 BURKETOM01        Tom     Burke        USA
2 HOFMAFRI01      Fritz   Hofmann        DEU
3  LANEFRA01    Francis      Lane        USA
4 SZOKOALA01     Alajos  Szokolyi        HUN
5 BURKETOM01        Tom     Burke        USA
6 JAMISHER01    Herbert   Jamison        USA

这就是奖牌的一部分：

year         sport    event athlete_id  medal

1 1896 Track & Field 100m Men BURKETOM01   GOLD
2 1896 Track & Field 100m Men HOFMAFRI01 SILVER
3 1896 Track & Field 100m Men  LANEFRA01 BRONZE
4 1896 Track & Field 100m Men SZOKOALA01 BRONZE
5 1896 Track & Field 400m Men BURKETOM01   GOLD
6 1896 Track & Field 400m Men JAMISHER01 SILVER

我需要找到奖牌数量最多的运动员和他赢得的奖牌数量。正确的答案是

 full_name top_no_medals
1 Larisa Latynina 18

我看到了一些与此类似的帖子并尝试使用那里建议的内容这是我的代码：

dbGetQuery(olympics.db,statement = 
             'SELECT Athletes.first_name ||" "|| Athletes.last_name AS full_name,COUNT(Medals.athlete_id) 
           AS top_no_medals
           FROM Athletes
           JOIN  Medals ON Medals.athlete_id=Athletes.athlete_id
           GROUP BY full_name
           ORDER BY COUNT(*) DESC
           LIMIT 1'
)

我要做的是根据变量athlete_id和计数这个变量组合2个表。出于某种原因，我得到的答案是奖牌太多了。

          full_name top_no_medals
1   Larisa Latynina           324

似乎在宣传奖牌时出现了错误。现在我确定数据是正确的，当我检查奖牌表看什么是最常见的运动员_我得到了正确的运动员。这是代码和答案：

dbGetQuery(olympics.db,statement = ' Select athlete_id, count(*) AS top_no_medals
 From Medals
Group By athlete_id
ORDER BY COUNT(*) DESC
LIMIT 1')

 athlete_id top_no_medals
1 LATYNLAR01            18

这名运动员是与Larisa Latynina有关的运动员，所以这不是问题在奖牌表中。

Answer 1

基于您的第二个查询有效的问题，问题似乎是列athletes(athlete_id)。这似乎是重复的。

尝试运行此查询：

select athlete_id, count(*) as cnt
from athletes
group by athlete_id
order by count(*) desc;

最大cnt应为1.如果不是，则表示您的数据存在问题。

哦，别担心。您的Atheletes表有重复项。假设名称始终相同，您可以这样做：

SELECT a.full_name, COUNT(*) AS top_no_medals
FROM (SELECT a.athlete_id,
             MAX(a.first_name || ' ' || a.last_name) as full_name
      FROM Athletes a 
      GROUP BY athlete_id
     ) a
     Medals m
     ON m.athlete_id = a.athlete_id
GROUP BY full_name
ORDER BY COUNT(*) DESC
LIMIT 1;

您还可以修改查询以使用COUNT(DISTINCT)，假设每个奖牌都有唯一标识符：

SELECT a.first_name || ' ' || a.last_name AS full_name,
       COUNT(DISTINCT m.medal_id) as top_no_medals
FROM Athletes a JOIN
     Medals m
     ON m.athlete_id = a.athlete_id
GROUP BY full_name
ORDER BY COUNT(DISTINCT m.medal_id) DESC
LIMIT 1;

Answer 2

鉴于第二个查询（获得奖牌计数）有效，我建议首先计算它然后加入运动员以获得与该ID匹配的名称：

SELECT a.first_name || ' ' || a.last_name AS full_name, top_no_medals
FROM (SELECT athlete_id, count(*) AS top_no_medals
      FROM Medals
      GROUP BY athlete_id
      ORDER BY COUNT(*) DESC
      LIMIT 1) m
JOIN Athletes a ON m.athlete_id = a.athlete_id

使用R中的Sqlite获取列中最常见的值

2 个答案: