user: Question: What was date of the game when the record was 31-15?
Columns: ['Date', 'Opponent', 'Score', 'Loss', 'Record']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['May 1', 'Rangers', '10 - 4', 'Tanana (2-3)', '14-9']
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "Record" = '31-15';