user: Question: Ram Vaswani was a winner on what date?
Columns: ['Date', 'City', 'Event', 'Winner', 'Prize']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['18 September 2004', 'Barcelona', 'Barcelona Open 2004', 'Alexander Stevic', '€80,000']
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "Winner" = 'Ram Vaswani';