user: Question: What date did the Home team score 11.21 (87)?
Columns: ['Home team', 'Home team score', 'Away team', 'Away team score', 'Venue', 'Crowd', 'Date']
Types: ['text', 'text', 'text', 'text', 'text', 'real', 'text']
Sample row: ['North Melbourne', '11.18 (84)', 'Hawthorn', '8.9 (57)', 'Arden Street Oval', 9000.0, '31 July 1948']
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "Home team score" = '11.21 (87)';