user: Question: Nigeria competed on July2, 1999.
Columns: ['Rank', 'Fastest time (s)', 'Wind (m/s)', 'Athlete', 'Nation', 'Date', 'Location']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, '10.88', '+2.0', 'Marlies Göhr', 'East Germany', '1 July 1977', 'Dresden']
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "Nation" = 'Nigeria';