Question

表格如下

Company, Vertical, Counts

对于每个公司，我希望根据具有最高计数的特定垂直来获得计数的总和

Company       Vertical             Counts 
IBM           Finance              10
IBM           R&D                   5
IBM           PR                    2

我想获得以下输出

IBM       Finance   17

Answer 1

自我加入应该这样做。

select company, vertical, total_count
from(
    select sum(counts) as total_count
    from table
    )a
cross join table
where counts=(select max(counts) from table);

根据您的RDBMS，您还可以使用窗口函数（例如sum（count）over（）作为total_count），而不必担心交叉连接。

Answer 2

这是对"How to get the MAX row"（DBA.SE链接）

问题的一种扭曲

以简单汇总方式获得每个公司的总垂直和最高垂直
使用这些来标识源表中的行

像这样，未经测试的

SELECT
    t.Company, t.Vertical, m.CompanyCount
FROM
    ( --get total and highest vertical  per Company
    SELECT
        COUNT(*) AS CompanyCount,
        MAX(Vertical) AS CompanyMaxVertical,
        Company
    FROM MyTable
    GROUP BY Company
    ) m
    JOIN --back to get the row for that company with  highest vertical
    MyTable t ON m.Company = t.Company AND m.CompanyMaxVertical = t.Vertical

编辑：这比标准SQL更接近ROW_NUMBER因为我们不知道平台

Answer 3

select Company,
       Vertical,
       SumCounts
from (       
        select Company,
               Vertical,
               row_number() over(partition by Company order by Counts desc) as rn,
               sum(Counts) over(partition by Company) as SumCounts
        from YourTable
     ) as T
where rn = 1

Answer 4

SELECT company,
       vertical,
       total_sum
FROM (
    SELECT Company, 
           Vertical, 
           sum(counts) over (partition by null) as total_sum,
           rank() over (order by counts desc) as count_rank
    FROM the_table
) t
WHERE count_rank = 1

选择具有约束的列的最大值

4 个答案: