Daily usage query

[coffman34]

I have a table that has multiple energy use readings throughout the day. So each day may have multiple readings.

How do I create a query to show daily usage?

I need to subtract the max record of X day from the max record from the previous day to ensure I include overnight usage (when no readings are taken).

[ranman256]

on a form, put a text box for current date, txtDate (date picker)
put a text box for prev date, txtPrevDate
txtPRevDate = DateAdd("d",-1,txtDate)

select the date.
Q1: select Max(reading) as PrevVal from table where [dateval]=forms!myForm!txtPrevDate
Q2: select Max(reading) as CurrVal from table where [dateval]=forms!myForm!txtDate
Q3: ,select Q2.CurrVal - Q1.PrevVAl from Q1,Q2

[ssanfu]

Kinda slim on info..... but it soulds like you will need a sub query to get the data.
You should see this about sub queries:

Get the value in another record
http://www.allenbrowne.com/subquery-...#AnotherRecord

Using this page, I was able to create a "Mileage" dB (using Access 97) to calculate/track mpg, cost & number of days between fill ups.