user: Question: On what date was there a game in which the opponent was the Detroit Tigers, and the attendance was 38,639?
Columns: ['Date', 'Opponent', 'Score', 'Loss', 'Attendance', 'Record']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['August 1', 'New York Yankees', '2-5', 'Moyer (8-8)', '53,840', '48-61']
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "Opponent" = 'Detroit Tigers' AND "Attendance" = '38,639';