MIN returns the lowest value from a group of values. The group is determined by the FROM clause that follows and may represent all records or a subset. All is the default.
In its most basic form, the MIN returns the minimum field value in all records returned by the rest of the query.
MIN( <field-name> ) FROM <from-clause>
The following field example returns the earliest donation date for Donor:
(SELECT MIN(D.Donation_Date) FROM Donations D WHERE D.Donor_ID = Donors.Donor_ID) AS [First Donation]