user: ### NOW ANSWER:
Question: What year was first elected William M. Wheeler (D) Unopposed?
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Result', 'Candidates']
Types: ['text', 'text', 'text', 'real', 'text', 'text']
Sample row: ['Georgia 1', 'Prince Hulon Preston, Jr.', 'Democratic', 1946.0, 'Re-elected', 'Prince Hulon Preston, Jr. (D) Unopposed']
SQL:

assistant: SELECT "First elected" FROM "Table" WHERE "Candidates" = 'William M. Wheeler (D) Unopposed';