Difference Between Two Entries

[MFS]

Need some help,
I have a table where data only comes in via a PLC at midnight every night.
One field is "Totalized_Gas_Usage" This is simply a growing number, never decreases will only increase.
What I am looking for is to add a field within the query that shows the difference between each entry.
Example : Yesterdays Totalized gas usage was 100, todays is 110, The difference is 10.

My query also shows all of current months data by day,

Can this be done ?

Thank You in advance

[pbaldy]

This will let you get the previous value in the same record so you can do math on it:

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

[MFS]

Thank you pbaldy once again for your support

[pbaldy]

Happy to help.