Question

我有一个包含产品订单的数据库，我需要将男性订单除以每年的所有订单。

我成功地打印了每年的所有订单和每年的男士订单，但是我不知道如何显示将数字相除的数字。

SELECT 
    YEAR(o.Order_Date) AS year,
    COUNT(o.order_id) AS number_of_orders
FROM
    [targil 2].[dbo].[exc2 - product] p, [targil 2].[dbo].[exc2 - orders] o
WHERE 
    p.Product_ID = o.Product_ID 
GROUP BY
    YEAR(o.Order_Date);

输出=

   year    number_of_orders
   -------------------------
   2012        540
   2013        512
   2014        180

SELECT DISTCINT
    YEAR(o.Order_Date) AS year, 
    COUNT(o.order_id) AS number_of_orders
FROM
    [targil 2].[dbo].[exc2 - product] p, [targil 2].[dbo].[exc2 - orders] o
WHERE 
    p.Product_ID = o.Product_ID 
    AND p.Product_Name LIKE '%men%'
GROUP BY
    YEAR(o.Order_Date);

输出

year  number_of_orders
----------------------
2012       50
2013      146
2014      138

所需的输出

year   number_of_men_orders_of_all_orders
----------------------------------------
2012        0.0925
2013        0.285
2014        0.766

Answer 1

您使用的是哪种SQL？看起来像MS Sql Server。

您必须将自己年份的两个结果集合并在一起，以便可以比较每个结果集的计数。尝试这样的事情：

WITH all_orders AS (
    SELECT YEAR(Order_Date) 'Year', COUNT(*) 'Count'
    FROM [targil 2].[dbo].[exc2 - orders]
    GROUP BY YEAR(Order_Date)
), men_orders AS (
    SELECT YEAR(o.Order_Date) 'Year', COUNT(*) 'Count'
    FROM [targil 2].[dbo].[exc2 - orders] o
    JOIN [targil 2].[dbo].[exc2 - product] p
        ON p.Product_ID = o.Product_ID
    WHERE p.Product_Name LIKE '%men%'
    GROUP BY YEAR(o.Order_Date)
)
SELECT
    COALESCE(a.Year, m.Year) 'Year',
    a.Count 'All Count',
    m.Count 'Men Count',
    CAST(ISNULL(m.Count, 0) AS DECIMAL) / CAST(a.Count AS DECIMAL) 'Ratio'
FROM all_orders a
LEFT JOIN men_orders m ON m.Year = a.Year

Answer 2

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用SQL除数

2 个答案: