Hi Paul you have given someone a solution "ways to calculate difference between numerical records."
I am very new at this you mentioned to use SQL and this was the
SELECT MeterReadings.MeterID, MeterReadings.Date, MeterReadings.Reading, (SELECT Reading FROM MeterReadings AS Alias WHERE Alias.MeterID = MeterReadings.MeterID AND Alias.Date = (SELECT Max(Date) FROM MeterReadings AS Alias2 WHERE Alias2.MeterID = MeterReadings.MeterID AND Alias2.Date < MeterReadings.Date)) AS PrevReading, [Reading]-[PrevReading] AS Diff
FROM MeterReadings
ORDER BY MeterReadings.MeterID, MeterReadings.Date
The Fields I use are [WellsDate]and [Main Meter] from my "tblWells" i also have many meters too if there is an easy way to combine them all in one would be great? and i am looking for it to be in a user choice referance too if it is possible? i changed most of it but it still does not work and i know i have done something wrong please help me