user: Question: What surface was the April 24, 2003 match played on?
Columns: ['Edition', 'Round', 'Date', 'Surface', 'Opponent', 'Result']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['1991 World Group I', 'R1', 'July 22, 1991', 'Hard', 'Petra Schmitt', '6–1, 6–2']
SQL:

assistant: SELECT "Surface" FROM "Table" WHERE "Date" = 'April 24, 2003';