What is the date where the winner was the Oakland Raiders in 1975?
CREATE TABLE "1970s_raiders_12_6_2" (
  "year" real,
  "date" text,
  "winner" text,
  "result" text,
  "loser" text,
  "location" text
);
SELECT "date" FROM "1970s_raiders_12_6_2" WHERE "year"=1975 AND "winner"='oakland raiders';