user: Question: How many deciles have Years of 1–8, and a Roll of 49?
Columns: ['Name', 'Years', 'Gender', 'Area', 'Authority', 'Decile', 'Roll']
Types: ['text', 'text', 'text', 'text', 'text', 'real', 'real']
Sample row: ['Allenton School', '1–6', 'Coed', 'Ashburton', 'State', 8.0, 343.0]
SQL:

assistant: SELECT COUNT("Decile") FROM "Table" WHERE "Years" = '1–8' AND "Roll" = 49.0;