user: Question: What year was Otto Passman (D) Unopposed first elected?
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Result', 'Candidates']
Types: ['text', 'text', 'text', 'real', 'text', 'text']
Sample row: ['Louisiana 1', 'F. Edward Hebert', 'Democratic', 1940.0, 'Re-elected', 'F. Edward Hebert (D) Unopposed']
SQL:

assistant: SELECT "First elected" FROM "Table" WHERE "Candidates" = 'Otto Passman (D) Unopposed';