user: Question: Which Democratic incumbent was first elected in 1998?
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Results']
Types: ['text', 'text', 'text', 'real', 'text']
Sample row: ['Oregon 1', 'David Wu', 'Democratic', 1998.0, 'Re-elected']
SQL:

assistant: SELECT "Incumbent" FROM "Table" WHERE "Party" = 'Democratic' AND "First elected" = 1998.0;