user: Question: How many dates was Knockhill?
Columns: ['Round', 'Circuit', 'Date', 'Pole Position', 'Fastest Lap', 'Winning Rider', 'Winning Team']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, 'Brands Hatch Indy', 'April 5', 'Billy McConnell', 'Sam Lowes', 'Sam Lowes', 'GNS Racing']
SQL:

assistant: SELECT COUNT("Date") FROM "Table" WHERE "Circuit" = 'Knockhill';