Calculate from previous row

[JoeyGaspard]

I have a table, and each row is a meter reading, I need to subtract the previous days reading to get a total usage. Here is a screenshot of the table:

I need to subtract todays meter reading from yesterdays to get a total usage for the last day? Any help on this would be great! Thanks in advance!

 

[Micron]

You'll need a subquery. Meter reading is actually one of the examples given here

Microsoft Access tips: Subquery basics

Using subqueries in Microsoft Access. What subqueries are, and examples of using subqueries.

allenbrowne.com

If there can be more than one meter with that name, then you have a design problem. Same goes for if you have one table per meter.

 

[JoeyGaspard]

You'll need a subquery. Meter reading is actually one of the examples given here

Microsoft Access tips: Subquery basics

Using subqueries in Microsoft Access. What subqueries are, and examples of using subqueries.

allenbrowne.com

If there can be more than one meter with that name, then you have a design problem. Same goes for if you have one table per meter.

There will not be duplicate meter names. I have a query that selects a start and end date (01/01/2022 and 01/02/2022), with those results I need to be able to subtract one from the other and display it on my report

 

[Micron]

If you can do it in a report it would probably involve code in the print event. While there is a running sum feature, AFAIK there is no such thing as a running difference. Much simpler to use a subquery in your report query, methinks.