CREATE TABLE "united_states_house_of_representatives_e" (
  "district" text,
  "incumbent" text,
  "party" text,
  "first_elected" real,
  "result" text,
  "candidates" text
);

Question: When was incumbent William B. Oliver first elected?
SQL: SELECT MAX("first_elected") FROM "united_states_house_of_representatives_e" WHERE "incumbent"='William B. Oliver';