Calculating water usage from current and previous record

[Jon_Stephenson]

I have a table with a date and numeric field. It tracks a water meter reading. Is there any way that I can calculate usage by taking the current record meter reading and comparing the difference between that and the previous records meter reading then calculating the number of days difference between the current and previous record to come up with a litres usage per day?

Thanks in advance.

[Bill_French]

Jon_Stephenson:

Is there any way that I can calculate usage by taking the current record meter reading and comparing the difference between that and the previous records meter reading

Yes, but the only way I know of doing this is with a script block.

[Jon_Stephenson]

Thanks - I feared that.