如何计算带有多个变量的 Futuation % select 语句？

Question

我需要逐月为波动报告编写查询。 对于每月消耗量，我有用于计算消耗量的开始和结束读数。 根据这个计算值，我需要找到每月的波动。

使用的代码

select distinct
c.CNAME as MeterPointName,
m.SNUMBER as SerialNumber,
bill.RDATE as BillingPeriod,
IF(bill.E1 > bill1.E1 and bill.BRID = bill1.BRID, (bill.E1 - bill1.E1), 0) as Consumption,
IF(bill.E1 > bill1.E1 and DATE(bill.RDATE) > DATE(bill1.RDATE), ((bill.E1 - bill1.E1)/(bill.E1-bill1.E1)), 0)  as Fluctuation

from table1.CUSTOMER c
RIGHT JOIN table2.METER m on c.CNUMBER = m.MNAME
LEFT JOIN table3.BILLMTOTAL bill on m.MNAME = bill.CNUMBER
LEFT JOIN table3.BILLMTOTAL bill1 on bill.SNUMBER = bill1.SNUMBER
RIGHT JOIN table4.CUSTOMERTREE cust on c.ID = cust.Customer_id
where bill.RP = 'E'
and bill1.RP = 'S'
and bill.BRID between 179 and 190
and bill.BRID = bill1.BRID
and date(bill.RDATE) > date(bill1.RDATE) 
and cust.lft between 2185 and 2633
GROUP BY m.SNUMBER, bill.BRID, bill.E1
ORDER BY bill.RDATE

bill1.E1 和 bill2.E1 是开始和结束读数。

例子：

账单.E1 - 5 账单.E2 - 10

一切正常，只是波动数字不正确。