Question: Who were the incumbent(s) in the election featuring  John Murray (DR) 50.4% George Denison (DR) 49.6% with a result of a Retired Democratic-Republican hold?
SQL: SELECT "Incumbent" FROM "1-2668336-19" WHERE "Candidates" = 'John Murray (DR) 50.4% George Denison (DR) 49.6%' AND "Result" = 'Retired Democratic-Republican hold';

Question: Who were the incumbent(s) when the result was a Retired Democratic-Republican hold and the first elected representative was in 1816>
SQL: SELECT "Incumbent" FROM "1-2668336-19" WHERE "Result" = 'Retired Democratic-Republican hold' AND "First elected" = '1816';

Question: Who were the candidates in the election where William Wilson was the incumbent?
SQL: SELECT "Candidates" FROM "1-2668336-19" WHERE "Incumbent" = 'William Wilson';