Report to only show first/last record of record group

Summary

I wish to only show one record (the most recent one) of all records having same values for col1, col2

Content

EDIT:

my example might have been confusing, so I'm adding a simplifies example:

let's say I'm trying to show the first incident each customer opened using these fields:

incidents.ref_no, contacts.email, incidents.created​

example:

10000,   a@a.a,   2019-04-29

21304,   b@b.b,  2019-04-29

can anyone please share a report definition that does it?

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Hi,

I have a report having the following columns: Email, OrderId, Date.

I want the report to only show the oldest record for the combination of (email, orderId).