Formula using previous record.

[n4467r]

I am new to this board and have a question.

I have a database set to log hours of use based on an hour meter. To calculate current record usage I would subtract the previous record meter reading from the current record meter reading. Entering a beginning meter reading would seem redundant but I have not been able to come up with a formula to satisfy this situation.

The result would be shown as usage on a report.

Thanks for the help.

David

 

[gol4]

using a sub query with an alias should do it assuming you have a read date as well

SELECT table1.reading - (select a.reading from table1 as a where a.hour - table1.hour -1 and a.readdate = table1.readdate)
from table1

may have to use dateadd to get you hours but the above shold be along the lines you want

 

[n4467r]

Thanks for the reply. Being a bit new to this stuff I am not sure I completely understand the syntax but if I play with it for a while I may just get it!

Thanks again....

David