user: Question: Which date did the Oakland Raiders play as the opponent when the Bills first downs were under 28?
Columns: ['Game', 'Date', 'Opponent', 'Result', 'Bills points', 'Opponents', 'Bills first downs', 'Record', 'Attendance']
Types: ['real', 'text', 'text', 'text', 'real', 'real', 'real', 'text', 'real']
Sample row: [1.0, 'Sept. 7', 'Miami Dolphins', 'Win', 17.0, 7.0, 22.0, '1–0', 79598.0]
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "Bills first downs" < 28.0 AND "Opponent" = 'Oakland Raiders';