Question

我有两个表，一个是Countries，其中包含codeCountry和nameCountry，第二个表Client包含privat_code_country. CodeCountry，例如AUS和nameCountry Austria

我想选择所有拥有最少客户数的国家/地区，换句话说，我必须加入这两个表格，找到所有拥有最少客户数量的国家/地区。

在我查询后，我遇到了“不是单组组功能”的问题。

这是我的疑问：

 select codeCountry, min(cnt) as Number_of_clients
from (select s.codeCountry, count(*) as cnt
      from countries s join
           client t
           on s.codeCountry = t.privat_code_country 
      group by s.codeCountry
     ) t order by number_of_clients desc, codeCountry asc;

我想收听所有客户数量最少的国家，所以我要求的是更正我的查询。 TNX

预期结果是：

CodeCountry Number    umber_of_clients
AUS                    1     
CRO                    1
ITA                    1

Answer 1

我并没有完全遵循你的逻辑，你的内部查询已经为每个codeCountry留下了1条记录，为什么你需要选择min（count）？

试试这个：

SELECT * FROM (
    select s.codeCountry, count(*) as number_of_clients 
    from countries s join
           client t
           on s.codeCountry = t.privat_code_country 
    group by s.codeCountry) tt
WHERE tt.number_of_clients = (select min(cnt) from(SELECT count(*) as cnt FROM countries s
                           join client t
                             on s.codeCountry = t.privat_code_country 
                           group by s.codeCountry))
order by tt.codeCountry asc;

我认为从数据的外观来看，您不必进行连接，只能从客户端表中进行选择：

SELECT * FROM (
    SELECT t.codeCountry,count(*) as number_of_clients
    FROM client t
    GROUP BY t.codeCountry) tt
WHERE tt.number_of_clients = (SELECT MIN(cnt) FROM(SELECT count(*) as cnt FROM client
                                                  GROUP BY codeCountry)
                             )

Answer 2

你需要一个RANK：

select *
from
 (
      select s.codeCountry, count(*) as cnt, 
         rank() over (order by count(*)) as rnk -- rank based on increasing counts
      from countries s join
           client t
           on s.codeCountry = t.privat_code_country 
      group by s.codeCountry
 ) dt 
where rnk = 1

Answer 3

如果您想要拥有最少客户数的国家/地区列表：

select x.codeCountry, x.cnt as number_of_clients 
from
(
    select t.codeCountry, min(t.cnt) over () as min_cnt, t.cnt
    from
    (
        select s.codeCountry, count(*) as cnt
        from 
        countries s 
        join 
        client t
        on s.codeCountry = t.privat_code_country 
        group by s.codeCountry

    ) t
) x
where x.cnt=x.min_cnt
order by codeCountry asc;

Answer 4

这是我所理解的。

select s.codeCountry, count(*) as cnt
  from countries s join client t
           on s.codeCountry = t.privat_code_country 
 group by s.codeCountry
 having count(1) > <the value you consider as minimum>
 order by s.codeCountry asc;

选择拥有最少客户数的所有国家/地区

4 个答案: