PostgreSQL计算当前行数值占总数的百分比

我将我的数据按seconditemid分组。是否有可能计算总数（所有表格数据的extcost合并）的各行的sum(extcost)百分比？PostgreSQL计算当前行数值占总数的百分比

例如我们在结果集中有2行，A1有总共4500，A2总共有5500，总数应该是10000，A1占45％，A2占55％。

seconditemid|ratio 
-------------------- 
A1   |.45 
-------------------- 
A2   |.55

我的查询是

select seconditemid, 
    round(100.0*(
     sum(case when seconditemid = ---the current row's seconditemid 
     then 1 else 0 end)/sum(extcost) 
    ),1) as ratio 
from inventory_fact f inner join item_master_dim i using (itemmasterkey) 
where transtypekey = 1 
group by seconditemid 
order by 2 desc;

这是行不通的。我试图创建一个视图第一

create view v1 as(
    select sum(extcost) as sumExtcost from inventory_fact 
);

，并从中选择

select seconditemid, round(100.0*(
     sum(extcost)/sum(v1.sumextcost) 
    ),1) as ratio 
from from inventory_fact f inner join item_master_dim i using (itemmasterkey), v1 
where transtypekey = 1 
group by seconditemid 
order by 2 desc;

那么每列的比为0

来源

2017-03-16 Dylan Czenski

的2D查询似乎罚款，你确定每个项目具有值的> = 10％？你只能在点后四舍五入到第一位 – cur4so

让我们这个示例模式：

CREATE TABLE c (
    seconditemid text, 
    total int 
); 

INSERT INTO c (seconditemid, total) VALUES ('A1', 4500); 
INSERT INTO c (seconditemid, total) VALUES ('A2', 5500);

以下是查询：

SELECT seconditemid, total, 
     total::float/(SUM(total) OVER()) as ratio 
FROM c;

- >

seconditemid | total | ratio 
--------------+-------+------- 
A1   | 4500 | 0.45 
A2   | 5500 | 0.55 
(2 rows)

来源

2017-03-16 21:36:41 Gab

你的第二个查询应该没问题，但你得到了0的背部因为integer division truncates the results。您需要明确地将总和值转换为float。

这里是没有视图的示例

SELECT g.seconditemid, g.extcost::float/t.total::float percent -- << here 
    FROM (
    SELECT seconditemid, SUM(extcost) extcost 
    FROM inventory_fact 
    GROUP BY seconditemid 
) g CROSS JOIN (
    SELECT SUM(extcost) total 
    FROM inventory_fact 
) t 
ORDER BY percent DESC

输出：

 
| seconditemid | percent | 
|--------------|---------| 
|   A2 | 0.55 | 
|   A1 | 0.45 |

SQLFiddle

来源

2017-03-16 21:45:42 peterm

PostgreSQL计算当前行数值占总数的百分比

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