How to calculate usage from start date to end date.

[Guest]

have a table set up (based on an the old EXCEL spreadsheet we used prior to
this)and I would like to be able to have the total gallons used calculated
from the beginning of a particular period to the end, by subtracting the
starting H20Meter reading by the ending H20 Meter reading. This is how my
table is set up:

GWID-autonumber
Date - Date/Time
Employee, Text
H20MeterReading - Number, long
GPM - Number, long (In excel, this field is popluated by subtracting last
H20 meter reading from previous.
24HRGAL-Number, long

Is the query or report the place to do this. Please let me know what I need
to do to fix this if I am wrong, etc. I am a newbie so please be gentle

 

[Allen Browne]

Use a query to get the difference between the current record and the
previous one, and then use the query as the source for your report.

Details in:
Referring to a Field in the Previous Record or Next Record
at:
http://support.microsoft.com/default.aspx?scid=kb;en-us;210504