Who was the partner of the winner?
CREATE TABLE "doubles_5_1_4" (
  "outcome" text,
  "date" text,
  "tournament" text,
  "surface" text,
  "partner" text,
  "opponent_in_final" text,
  "score_in_final" text
);
SELECT "partner" FROM "doubles_5_1_4" WHERE "outcome"='winner';