I have a db where I have the following fields:
log_date log_hour number
10/15/13 24:00 12345
10/16/13 01:00 12356
There are 24 hours for each day so I have 24 records for each day starting with 01:00 and ending with 24:00. I am trying to use the number from let's say hour 01:00 and subtract from the number in hour 02:00. My calculation works by subracting the number field between log_hour "02:00" and log hour "01:00". I used relationships to provide the basis for the calculations for the hours during the same day but to get the last hour from the previous day seems to be beyond my brain power at the moment. This works fine until I try to subtract the 01:00 hour from the 24:00 hour from the previous day. I know I am missing something simple but for the life of me I can't figure that one out.