具有合并和左外部联接的SQL查询

很抱歉打扰您，但我被sqlite查询卡住了：(

我有一张桌子：

sport country place type
ski  swe 1 1
ski  nor 2 1
ski  rus 3 1
luge swe 1 1
luge usa 2 1
luge ger 3 1
bob  nor 1 1
bob  rus 2 1
bob  ger 3 1

其中1为金，2为银，3为铜

现在，正常的显示场景是一个国家列表，首先是max gold，然后是silver，然后是bronze。例如：

swe g:2 s:0 b:0 sum:2
rus g:0 s:1 b:1 sum:2
usa g:0 s:1 b:0 sum:1
nor g:0 s:0 b:2 sum:2

为此，我正在做：

select
    country,
    sum(case when place = 1 then 1 else 0 end) as gold,
    sum(case when place = 2 then 1 else 0 end) as silver,
    sum(case when place = 3 then 1 else 0 end) as bronce,
    count(*) as allmedals
from 
    results 
group by 
    country 
order by 
    gold DESC, silver DESC, bronce DESC

到目前为止还可以。但我有另一个表“国家”，全名，简称和一些“类型”

我想将“结果”表和“国家”表合并起来，这样我就可以列出“国家”表中的所有结果，如果没有结果，那么它只是一个0。因此我尝试：

SELECT 
    c.name as c_name,
    COALESCE(sum(case when r.place = 1 then 1 else 0 end), 0) as gold,
    COALESCE(sum(case when r.place = 2 then 1 else 0 end), 0) as silver,
    COALESCE(sum(case when r.place = 3 then 1 else 0 end), 0) as bronce
FROM 
    countries AS c 
LEFT OUTER JOIN 
    results AS r ON c.short = r.country 
WHERE 
    r.type = 1 
GROUP BY 
    r.country
ORDER BY 
    gold DESC, silver DESC, bronce DESC, c.name DESC" 

但问题是，我只看到一个国家的列表，在“结果”表中有一行。我认为这是因为“r.type=1”

尝试更改

LEFT OUTER JOIN results as r ON c.short = r.country 
WHERE r.type = 1

到

这对我很管用

select 
c.name,
sum(case when place = 1 then 1 else 0 end) as gold,
sum(case when place = 2 then 1 else 0 end) as silver,
sum(case when place = 3 then 1 else 0 end) as bronce,
count(*) as allmedals
from countries  c 
left outer join results r on c.short = r.country
group by c.name
order by gold desc, silver desc, broncedesc, c.name desc

---

！！！！！！！这就是解决方案！！！！！事实上我不知道，在JOIN中允许执行多个操作。非常感谢。我不明白“不，它不起作用！！！它只显示一行接一行的结果！”的意思。很抱歉评论不清。例如，我在“国家”表中有5个国家：瑞典、俄罗斯、美国、挪威、斯洛文尼亚…在“结果”中只有2行：swe和rus。然后显示3行。swe、rus和usa（最早由c.name DESC发现）。“分组依据”是一个问题，我认为是“分组依据r.country”@user1908375啊，我明白了。你明白为什么这是个问题吗？你在结果表中按数据分组，你的外部联接，其中国家的所有数据，对于该表中不存在的行都是空的。因此是单行。很抱歉，我应该能够挑出它。请使用更多信息进行编辑。仅编码并“尝试此”答案是不鼓励的，因为它们不包含可搜索的内容，并且没有解释为什么有人应该“尝试这个”。

LEFT OUTER JOIN results as r ON c.short = r.country and r.type = 1

select 
c.name,
sum(case when place = 1 then 1 else 0 end) as gold,
sum(case when place = 2 then 1 else 0 end) as silver,
sum(case when place = 3 then 1 else 0 end) as bronce,
count(*) as allmedals
from countries  c 
left outer join results r on c.short = r.country
group by c.name
order by gold desc, silver desc, broncedesc, c.name desc

SELECT 
     c.name,
     SUM(CASE WHEN place = 1 THEN 1 ELSE 0 END) AS gold,
     sum(CASE WHEN place = 2 THEN 1 ELSE 0 END) AS silver,
     sum(CASE WHEN place = 3 THEN 1 ELSE 0 END) AS bronce,
     IFNULL (COUNT(r.country), 0) AS allmedals
FROM countries  c 
   LEFT OUTER JOIN records AS r ON c.short = r.country 
GROUP BY c.name
ORDER BY c.name asc;