What is the total number of First Elected, when Party is "Democratic", and when District is "Tennessee 5"?
CREATE TABLE "tennessee" (
  "district" text,
  "incumbent" text,
  "party" text,
  "first_elected" real,
  "results" text
);
SELECT COUNT("first_elected") FROM "tennessee" WHERE "party"='democratic' AND "district"='tennessee 5';