user: Question: What rounds did Roy Salvadori drive for David Brown Corporation?
Columns: ['Entrant', 'Constructor', 'Chassis', 'Engine', 'Tyre', 'Driver', 'Rounds']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Camoradi International', 'Behra-Porsche - Porsche', 'RSK', 'Porsche 547/6 1.5 F4', 'D', 'Masten Gregory', '1']
SQL:

assistant: SELECT "Rounds" FROM "Table" WHERE "Entrant" = 'David Brown Corporation' AND "Driver" = 'Roy Salvadori';