how a query can calculate difference of new odometer & last odometer (1 Viewer)

[irslan rafique]

Hi guys,
I am designing mileage database in access 2010.
table:
1- maintbl (date, truckNo fillinQty,rate,cost, odometer, mileage)

Query:
1- mainquery (based on maintbl)

Form:
1- mainfrm (Based on mainquery)

i want to calculate mileage :
example:new odometer reading - previous odometer reading / filled in qty
example: 2000 km - 1000 km / 200 liters = 5 liters /km

Objective: How query will automatically calculate the difference of new odometer reading and last odometer reading for a specific truck number and divide it with filled in qty of fuel?

Please help out me as i have wasted a lot of days.
I will be very thankful to u for prompt guidance.

 

[pbaldy]

How about:

http://allenbrowne.com/subquery-01.html#AnotherRecord

 

[irslan rafique]

I couldn't find anything supportive there..My apology.But please somebody help out me.