Question

基本上我有一个包含多个列的表，但我只对4感兴趣。我的表看起来像这样：

accountID productID profit cost date       country     city   quantity
        2        10     25   15 2017/03/13 Afghanistan Kabul       330
       18         3     45   42 2017/05/14 UK          London     5300
       25        14     22   17 2017/05/21 UK          London      300
        3        11     30   26 2017/04/23 Afghanistan Herat       400

我想要达到的目标是按城市，国家和city_quantity / country_quantity的比例获得产品总数：

 country     city    city_quantity country_quantity   city_percentage
Afghanistan Kabul        800            1400              0.57 
Afghanistan Kandahar     400            1400              0.29
Afghanistan Herat        200            1400              0.14
UK        London         6500           10000             0.65
UK        Manchester     3000           10000             0.3
UK        Newcastle       500           10000             0.05

到目前为止，我的脚本看起来像这样：

select country, city, sum(quantity)
from table
where date > dateadd(month,-1,getdate())
group by country, city
order by country, city

where条件是因为我只想要上个月的数据所以认为它无关紧要。

如何通过简单的脚本实现我想要的目标？

Answer 1

您可以使用自我加入来对按国家/地区分组的数量求和，然后使用该值来计算百分比，如下所示：

CREATE TABLE testTable (country VARCHAR(2), city CHAR(1), quantity DECIMAL(10,2));

INSERT INTO testTable (country, city, quantity)
VALUES
('Af', 'K', 330),
('Af', 'H', 400),
('Af', 'Q', 700),
('UK', 'L', 1000),
('UK', 'M', 500);

SELECT t.country, t.city, t.quantity AS city_quantity, q.qty AS country_quantity, 
       CAST(t.quantity / q.qty AS DECIMAL(10,2)) AS city_percentage
FROM testTable t
JOIN
(
  SELECT z.country, SUM(z.quantity) qty
  FROM testTable z
  GROUP BY z.country
) q ON t.country = q.country

这将为您提供所需的结果集：

+---------+------+--------------+-----------------+-----------------+
| country | city | city_quantity| country_quantity| city_percentage |
+---------+------+--------------+-----------------+-----------------+
| Af      | K    |          330 |            1430 | 0.23            |
| Af      | H    |          400 |            1430 | 0.28            |
| Af      | Q    |          700 |            1430 | 0.49            |
| UK      | L    |         1000 |            1500 | 0.67            |
| UK      | M    |          500 |            1500 | 0.33            |
+---------+------+--------------+-----------------+-----------------+

请记住，您要在任何生产查询中检查除以零。

SQL按结果将数字除以不同的组

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