CREATE TABLE people (people_id NUMBER, sex CLOB, name CLOB, date_of_birth CLOB, height NUMBER, weight NUMBER)
CREATE TABLE candidate (candidate_id NUMBER, people_id NUMBER, poll_source CLOB, date CLOB, support_rate NUMBER, consider_rate NUMBER, oppose_rate NUMBER, unsure_rate NUMBER)

Return the poll source corresponding to the candidate who has the oppose rate.
SELECT poll_source FROM candidate ORDER BY oppose_rate DESC LIMIT 1
SELECT "poll_source" FROM "candidate" ORDER BY "oppose_rate" DESC FETCH FIRST 1 ROWS ONLY