查找比上一年增加的百分比答案

【问题标题】：Find percentage increase from previous year查找比上一年增加的百分比
【发布时间】：2018-04-22 00:46:55
【问题描述】：

说实话，我不知道从哪里开始这个脚本。我可以从销售表中生成显示每月销售总收入的结果。

以下脚本：

SELECT coalesce(date_format(TRANSACTION_DATE, '%M'), 'Grand Total') AS MONTH,
ROUND(SUM(SALES_AMOUNT),2) TOTAL
FROM SALES
WHERE YEAR(TRANSACTION_DATE) = 2018
GROUP BY month

结果：（很好，工作正常）

Month   Total
January 45163.22
February    34531.15
March   44194.98
April   30826.68
May 39016.04
June    37284.25
July    37640.08
August  39703.85
September   34958.94
October 34447.61
November    39161.9
December    36986.16

但是，我想产生以下结果...即 Jan 为 NULL，而二月的差异为 -10632.07，相当于减少了 23.54%

        Difference  Percentage Increase/Decrease
January 45163.22        
February    34531.15    -10632.07   -23.54
March   44194.98    9663.83 27.99
April   30826.68    -13368.3    -30.25
May 39016.04    8189.36 26.57
June    37284.25    -1731.79    -4.44
July    37640.08    355.83  0.95
August  39703.85    2063.77 5.48
September   34958.94    -4744.91    -11.95
October 34447.61    -511.33 -1.46
November    39161.9 4714.29 13.69
December    36986.16    -2175.74    -5.56

希望这是有道理的，如果有人可以帮助我，那就太好了。

谢谢

【问题讨论】：

什么 MySQL 版本？

标签： mysql

【解决方案1】：

你可以使用连接

    select a.MONTH, a.TOTAL, a.TOTAL - b.TOTAL,  ((a.TOTAL - b.TOTAL)/ a.TOTAL )*100
    from (

    SELECT coalesce(date_format(TRANSACTION_DATE, '%M'), 'Grand Total') AS MONTH,
    ROUND(SUM(SALES_AMOUNT),2) TOTAL
    FROM SALES
    WHERE YEAR(TRANSACTION_DATE) = 2018
    GROUP BY month
     ) a
    inner  join (
    SELECT coalesce(date_format(TRANSACTION_DATE, '%M'), 'Grand Total') AS MONTH,
    ROUND(SUM(SALES_AMOUNT),2) TOTAL
    FROM SALES
    WHERE YEAR(TRANSACTION_DATE) = 2017
    GROUP BY month
     ) b ON a.month = b.month

【讨论】：

【解决方案2】：

通过在当月加入 SALES，并将第二次 SALES 限制在上一年，您将获得两年的匹配月份。

SELECT 
    coalesce(date_format(a.`TRANSACTION_DATE`, '%M'), 'Grand Total') AS `MONTH`,
    ROUND(SUM(a.`SALES_AMOUNT`),2) AS `TOTAL_2018`,
    ROUND(SUM(b.`SALES_AMOUNT`),2) AS `TOTAL_2017`,
    ROUND(SUM(a.`SALES_AMOUNT`),2) - ROUND(SUM(b.`SALES_AMOUNT`),2) AS `Difference`,
    ROUND((ROUND(SUM(a.`SALES_AMOUNT`),2) - ROUND(SUM(b.`SALES_AMOUNT`),2)) / ROUND(SUM(b.`SALES_AMOUNT`),2),2) AS `Percentage_Difference`
FROM `SALES` a
JOIN `SALES` b
ON YEAR(b.`TRANSACTION_DATE`) = YEAR(a.`TRANSACTION_DATE`) - 1 AND 
    MONTH(a.`TRANSACTION_DATE`) = MONTH(b.`TRANSACTION_DATE`)
WHERE YEAR(a.`TRANSACTION_DATE`) = 2018
GROUP BY a.coalesce(date_format(a.`TRANSACTION_DATE`, '%M'), 'Grand Total')
ORDER BY a.coalesce(date_format(a.`TRANSACTION_DATE`, '%M'), 'Grand Total');

请注意，通过删除 WHERE 子句并将年份添加到 group by 和 order by 子句，您可以生成多年的报告。

【讨论】：