Please help me if anyone have a solution for this
I have a database containing hundreds of records of a machine error logs
and i am creating a project in asp.net to show the performamnce of the equipments.

My Problem:I need to calculate and display the MTBF (mean time between faliures) using SQL statement.
That is calculating the mean time between entries and display the result for each machine.

Database table example:

date time errorcode machinename
19/7/2007 5:33:51 2.1117 CPT01
21/7/2007 4:15:16 2.1267 CPT01
19/7/2007 7:33:51 2.1117 CPT02
21/7/2007 8:15:16 2.1267 CPT02


I need the result to be something like this..

machinename MTBF
CPT01 2:23:45
CPT02 2:23:45

Thanks in advance