Martin
If your import file contains "Absences" (plural, so I assume this is a
number), and "Date" (I assume this is a single date), I don't see how you
could end up with what you asked for, "how many absences they have and on
what dates they were absent".
You didn't indicate if the "ID" field is unique to the source system, or is
a unique ID for the individual. That is, could "Smith, John" get imported,
over time, with more than one ID?
You are using a field named "Date" -- this is a reserved word in Access, and
will cause both you and Access to have severe headaches trying to figure out
whether you are referring to the Date() function or ...?
More info, please...

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Good luck
Jeff Boyce
<Access MVP