user: Question: When was incumbent John Thomas Wilson first elected? 
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Result', 'Candidates']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Ohio 7', 'Samuel Shellabarger', 'Republican', '1864', 'Retired Republican hold', 'James J. Winans (R) 50.2% John H. Thomas (D) 49.8%']
SQL:

assistant: SELECT "First elected" FROM "Table" WHERE "Incumbent" = 'John Thomas Wilson';