user: Question: Who was the winning driver when the grand Prix was at Belgian Grand Prix?
Columns: ['Round', 'Grand Prix', 'Pole Position', 'Fastest Lap', 'Winning Driver', 'Winning Constructor', 'Report']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, 'Brazilian Grand Prix', 'Ayrton Senna', 'Michael Schumacher', 'Michael Schumacher', 'Benetton - Ford', 'Report']
SQL:

assistant: SELECT "Winning Driver" FROM "Table" WHERE "Grand Prix" = 'Belgian Grand Prix';