Disregarding info in cells outside set time limits.

Hi,
I had a lot of help here last year and am now returning with another question.
A database at work, when asked for information, has given me the following info - I asked for the info to be in excel format for manipulation purposes.

Unfortunately the excel file generated has some cells that have data partly outside the parameters needed.

In the example attached, you can see that there is a start time, a finish time and the total time elapsed.

My problem is that I need, in this case, just to count the minutes elapsed from 06:00 hrs on the 8th Mar.

If I do it in my head it is 7 min 58 secs. - Easy you say - yes, but I have about 2000 rows of data to sift through!

Is there a formula or macro that can be run on all these 2000 cells to automatically disregard times that fall outside specifically set limits (in this case a 6:00 shift start time)?

Many thanks,
Clive.

Originally Posted by DonkeyOte

Can't you just use formulae, ie:

D2: =MAX(0,$B2-"08-Mar-2010 06:00")
format as [h]:mm:ss

Thanks, DonkeyOte - I'll give it a go!

Clive.