What is Incumbent, when Results is "Re-Elected", when Party is "Democratic", and when District is "Minnesota 7"?
CREATE TABLE "minnesota" (
  "district" text,
  "incumbent" text,
  "party" text,
  "first_elected" real,
  "results" text
);
SELECT "incumbent" FROM "minnesota" WHERE "results"='re-elected' AND "party"='democratic' AND "district"='minnesota 7';