CREATE TABLE table_28397 ("Institution" TEXT, "Location" TEXT, "Nickname" TEXT, "Founded" FLOAT, "Type" TEXT, "Enrollment" FLOAT, "Joined MAC" FLOAT)

What year did the the school with the nickname eagles join the mac?
SELECT MIN("Joined MAC") FROM table_28397 WHERE "Nickname" = 'Eagles'
SELECT MIN("Joined MAC") FROM "table_28397" WHERE "Nickname" = 'Eagles'