Distinct records within subreport???

[dwunz]

I have a collection of 3 reports...a primary and 2 subreports. In one of the subreports, I need to get distinct rows based on 2 of 3 fields (field 1 is a time stamp, and fields 2 and 3 are the fields that define distinctness)...field 2 is a substring (pos. 10 thru 29) of a 100 character field. Any idea how I can do this in CR8.5? I'm kinda new to CR, so be nice...
Thanks, don

 

[dwunz]

I forgot to add...this subreport also uses 2 parameters from the main report to use a start and end time as part of the selection.