SQL-使用groupby和分区进行聚合

Question

我有一张看起来像这样的桌子叫sales

 brand  | model    | sales           
--------+----------+------
 brand1 | model11  | 100
 brand1 | model11  | 300
 brand2 | model21  | 100
 brand2 | model22  | 400 
 brand3 | model31  | 100

我正在使用以下SQL查询

SELECT 
     brand, SUM(sales)/SUM(sales) OVER () as sales_share
FROM sales
GROUP BY brand

以便如下获得每个品牌的sales_share

 brand  | sales_share          
--------+--------------
 brand1 | 0.4
 brand2 | 0.5
 brand3 | 0.1

但是，我遇到错误Attribute SALES.sales must be GROUPed or used in an aggregate function -是否有任何指针？

Answer 1

以下作品

SELECT 
     brand, SUM(sales)/SUM(SUM(sales)) OVER () as sales_share
FROM sales
GROUP BY brand

最初尝试中缺少的是聚合功能-就像错误消息中所说的一样:)

Answer 2

如果使用的是sql，则应按选择的每个属性分组。 因此，您的查询将类似于：

SELECT 
     brand, SUM(sales)/SUM(sales) OVER () as sales_share
FROM sales
GROUP BY brand, sales

Answer 3

您可以使用，

select  
     brand, SUM(sales)as brand_sales
into tmp
from sales 
group by brand

select  brand , 
        total_sales /(select SUM(b.sales) from sales b) as total_sales 
from tmp 

drop table tmp

Answer 4

尝试这个 ：

  select brand , sales_share/sum(sales_share) over () sales_share from (
    SELECT 
       brand, SUM(sales)  as sales_share
    FROM sales
       GROUP BY brand
    ) a

Answer 5

您实际上并不需要窗口函数：

SELECT brand, 
       sum(sales) / (select sum(sales) from sales) as sales_share
FROM sales
GROUP BY brand;

根据sales的数据类型，您可能需要将其强制转换为小数，否则Postgres将使用整数除法

SQLFiddle： http ://sqlfiddle.com/#!15/548ad/1