Question

我在MySQL中有一个表，其中包含一个date，type，一个site_id和一个value 我想获得当年和去年的值的增/减，但我似乎无法做到这一点，

首先-如果不包含行lossOrGain (previousFill - currentFill) AS 'Increase/Decrease'，我如何实际减去这些值，我得到了我需要的值，但我无法如行中所示相互减去代码。

第二步-当我删除lossOrGain (previousFill - currentFill) AS 'Increase/Decrease'时，每个站点的值都相同，它仅采用第一个站点的值并将其应用于所有其他站点，

网站|先前值|当前值
A | 1 | 2
B | 1 | 2
C | 1 | 2

我该如何解决？

这是我第一次在MySQL中执行此操作，但我尝试执行类似操作但失败了

SELECT s.name AS SiteName,
(SELECT AVG(mi.value)
  FROM management_information mi
  WHERE mi.type = 'AVERAGE_FILL'
  AND mi.date
  BETWEEN DATE_SUB(:fromDate, INTERVAL 1 YEAR) AND DATE_SUB(:toDate, INTERVAL 1 YEAR)
  -
  SELECT AVG(mi.value)
  FROM management_information mi
  WHERE mi.type = 'AVERAGE_FILL'
  AND mi.date BETWEEN :fromDate AND :toDate)
AS 'Increase/Decrease'
FROM management_information mi
LEFT JOIN site s
ON mi.site_id = s.id
WHERE mi.type = 'AVERAGE_FILL'
AND mi.date BETWEEN :fromDate AND :toDate;

最后显示以下代码

(SELECT AVG(mi.value)
  FROM management_information mi
  WHERE mi.type = 'AVERAGE_FILL'
  AND mi.date BETWEEN DATE_SUB(:fromDate, INTERVAL 1 YEAR) AND DATE_SUB(:toDate, INTERVAL 1 YEAR)) previousFill,
(SELECT AVG(mi.value)
  FROM management_information mi
  WHERE mi.type = 'AVERAGE_FILL'
  AND mi.date BETWEEN :fromDate AND :toDate) currentFill,
lossOrGain (previousFill - currentFill) AS 'Increase/Decrease'
FROM management_information mi
LEFT JOIN site s
ON mi.site_id = s.id
WHERE mi.type = 'AVERAGE_FILL'
AND mi.date BETWEEN :fromDate AND :toDate;

我希望与去年相比，特定月份的所有网站的价值都有增减

网站：A
增/减：（去年的值-今年的值）

所以我需要帮助

正确掌握SQL中的数学运算以增加/减小值
获取每个站点的当年和去年的正确值

因为我很困惑，我该怎么办？

编辑：

我设法正确计算数学并获得了Increase/Decrease值，现在我需要为相关站点获取适当的值，这就是我所做的

SELECT s.name AS SiteName,
((SELECT AVG(mi.value)
  FROM management_information mi
  WHERE mi.type = 'AVERAGE_FILL'
  AND mi.date
  BETWEEN DATE_SUB(:fromDate, INTERVAL 1 YEAR) AND DATE_SUB(:toDate, INTERVAL 1 YEAR)) -
(SELECT AVG(mi.value)
  FROM management_information mi
  WHERE mi.type = 'AVERAGE_FILL'
  AND mi.date BETWEEN :fromDate AND :toDate)) AS 'Increase/Decrease'
FROM management_information mi
LEFT JOIN site s
ON mi.site_id = s.id
WHERE mi.type = 'AVERAGE_FILL'
AND mi.date BETWEEN :fromDate AND :toDate;

如何从当前年份和去年减去同一表中的2个值

0 个答案: