DB2部门

Question

您好我正在尝试计算卡车的MPG 这就是我所拥有的

SELECT DRIVER_ID, UNIT_ID, 
(SELECT SUM(T2.VOL_PFUEL) FROM FC_POS T2 WHERE T2.UNIT_ID = T1.UNIT_ID) AS CUMULATIVE_FUEL_PURCHASE,
(SELECT ODOMETER FROM ODOHIST O WHERE O.UNIT_ID = T1.UNIT_ID ORDER BY READINGDATE DESC FETCH FIRST ROW ONLY) AS ODOMETER,
((SELECT ODOMETER FROM ODOHIST O WHERE O.UNIT_ID = T1.UNIT_ID ORDER BY READINGDATE DESC FETCH FIRST ROW ONLY)/(SELECT SUM(T2.VOL_PFUEL) FROM FC_POS T2 WHERE T2.UNIT_ID = T1.UNIT_ID)) AS MPG
FROM FC_POS T1 WHERE UNIT_ID = '####'
ORDER BY POS_DATE DESC 
FETCH FIRST ROW ONLY
WITH UR

结果如下：

driver_id: ######
unit_id: #####
cumulative_fuel_purchase: 9180.56
odometer: 65701.3
MPG: 6779107157

所以当我用里程表划分cumulative_fuel_purchase时，我应该得到7.1而不是上面那个怪物！

我正在使用DB2 谢谢！