user: Question: Name the length for All class and date of March 18
Columns: ['Race', 'Length', 'Class', 'Circuit', 'Date']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Rolex 24 at Daytona', '24 Hours', 'All', 'Daytona International Speedway', 'February 4 February 5']
SQL:

assistant: SELECT "Length" FROM "Table" WHERE "Class" = 'All' AND "Date" = 'March 18';