Re: AW: SQL - Calculate the number of hours between 2 timestamps

Study that timestampdiff bif carefully.  A lot of assumptions are made. 
Which may, or may not, matter for your situation.  Straight from the book:

The following assumptions may be used in estimating the difference: 

there are 365 days in a year 
there are 30 days in a month 
there are 24 hours in a day 
there are 60 minutes in an hour 
there are 60 seconds in a minute
These assumptions are used when converting the information in the second 
argument, which is a timestamp duration, to the interval type specified in 
the first argument. The returned estimate may vary by a number of days. 
For example, if the number of days (interval 16) is requested for a 
difference in timestamps for '1997-03-01-00.00.00' and 
'1997-02-01-00.00.00', the result is 30. This is because the difference 
between the timestamps is 1 month so the assumption of 30 days in a month 
applies.


Rob Berendt