you need autonumber field.
on query:
this will start from I-0001:
Select autonumberfield, "I-" & Format(DCount("1","yourTable","autonumberField<=" & [autonumberfield]), "00000") As sequence From yourTable;
this will start from I-17088:
Select autonumberfield, "I-" & Format(DCount("1","yourTable","autonumberField<=" & [autonumberfield]) + 17087, "00000") As sequence From yourTable;