user: Question: What is the earliest year that had a Lotus 49B chassis?
Columns: ['Year', 'Entrant', 'Chassis', 'Engine', 'Points']
Types: ['real', 'text', 'text', 'text', 'real']
Sample row: [1964.0, 'Owen Racing Organisation', 'BRM P67', 'BRM V8', 0.0]
SQL:

assistant: SELECT MIN("Year") FROM "Table" WHERE "Chassis" = 'Lotus 49B';