user: Question: What is the date of the 1500m freestyle event?
Columns: ['Event', 'Time', 'Nationality', 'Date', 'Meet', 'Location']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['50m freestyle', '20.91', 'Brazil', '18 December 2009', 'Brazilian Championships', 'São Paulo , Brazil']
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "Event" = '1500m freestyle';