user: Question: What team was the home team when the away team scored 17.21 (123)?
Columns: ['Home team', 'Home team score', 'Away team', 'Away team score', 'Venue', 'Crowd', 'Date']
Types: ['text', 'text', 'text', 'text', 'text', 'real', 'text']
Sample row: ['Essendon', '16.15 (111)', 'North Melbourne', '15.9 (99)', 'Windy Hill', 26443.0, '4 April 1981']
SQL:

assistant: SELECT "Home team" FROM "Table" WHERE "Away team score" = '17.21 (123)';