user: Question: Who was the opponent on April 24, 1999?
Columns: ['Edition', 'Round', 'Date', 'Surface', 'Opponent', 'Result']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['1988 World Group I', 'QR', 'December 4, 1988', 'Hard', 'Sarah Rafael', '6–3, 6–2']
SQL:

assistant: SELECT "Opponent" FROM "Table" WHERE "Date" = 'April 24, 1999';