user: Question: Who won the race on August 15?
Columns: ['Round', 'Date', 'Grand Prix', 'Circuit', 'Pole Position', 'Fastest Lap', 'Race Winner']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, 'May 1', 'Spanish Grand Prix', 'Jerez', 'Daijiro Hiura', 'Daniel Ruiz', 'Danny Kent']
SQL:

assistant: SELECT "Race Winner" FROM "Table" WHERE "Date" = 'August 15';