user: Question: Which Entrant has a Vanwall Straight-4 engine?
Columns: ['Year', 'Entrant', 'Chassis', 'Engine', 'Points']
Types: ['real', 'text', 'text', 'text', 'real']
Sample row: [1950.0, 'SA Alfa Romeo', 'Alfa Romeo 158', 'Alfa Romeo Straight-8', 0.0]
SQL:

assistant: SELECT "Entrant" FROM "Table" WHERE "Engine" = 'Vanwall Straight-4';