I know I've read that dates and time don't do well in lists. Does anyone know a workaround to create a calculated column that will bump the number up in the column by 1 every 24 hours. So the column is titled # of days post-op and it will equal 0 on the first day, after 24 hours it should equal 1, etc.
As Aron mentioned if you wanted it to automatically update you'll need to configure something to periodically update the values.
- A SharePoint Timer Job that runs once a day to update the column.
- A PowerShell script to update the column that runs once a day via the Windows Scheduler.