Problem extracting specific info based on dates

[confused64]

Ok, here's my problem... using crystal reports 11 and trying to extract the earliest "start" date based on part of the "section" but only certain ones:
eg. section: start date:
abc-def-ghi-jk 12 jan 2011
abc-def-ghi-lm-no 15 oct 2010
abc-def-ghi-lm-gh 06 jul 2010
xyz-gh-yup-lm 05 feb 2009
abc-def-ghi-lm-pq 31 mar 2008

based on the core section of "abc-def-ghi", need to extract the date where that series of sections last started, 06 jul 2010, and NOT go back to the 31 mar 2008 one! is it possible? any thoughts?
One other thing - extracting from ms access database.

Thanks in advance

 

[lbass]

What do you need to do with the result? Do you need it displayed in a particular section? Or do you just need that row identified? Or do you need other rows suppressed? Or? Please provide context.

-LB

 

[confused64]

I am using that extracted date, subtracting from current date and displaying it, in years, for how long a person has been in that core section continuously.

 

[lbass]

But in what report section? Where do you want to display this calculation?

-LB