user: Question: what is the district with the candidates Edward Boland (D) Unopposed?
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Result', 'Candidates']
Types: ['text', 'text', 'text', 'real', 'text', 'text']
Sample row: ['Massachusetts 1', 'Silvio Conte', 'Republican', 1958.0, 'Re-elected', 'Silvio Conte (R) 71.1% Thomas R. Manning (D) 28.9%']
SQL:

assistant: SELECT "District" FROM "Table" WHERE "Candidates" = 'Edward Boland (D) Unopposed';