user: Question: Who was the visitor on March 21?
Columns: ['Date', 'Visitor', 'Score', 'Home', 'Decision', 'Attendance', 'Record']
Types: ['text', 'text', 'text', 'text', 'text', 'real', 'text']
Sample row: ['March 1', 'Detroit', '2 – 0', 'Anaheim', 'Osgood', 16606.0, '40–14–5']
SQL:

assistant: SELECT "Visitor" FROM "Table" WHERE "Date" = 'March 21';