user: Question: Name the winning driver for 20 April
Columns: ['Round', 'Circuit', 'Date', 'Pole Position', 'Fastest Lap', 'Winning driver', 'Winning team']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['1', 'Donington Park', '6 April', 'Jamie Green', 'Alan van der Merwe', 'Jamie Green', 'Carlin Motorsport']
SQL:

assistant: SELECT "Winning driver" FROM "Table" WHERE "Date" = '20 April';