What is Years, when Nationality is United States, and when Position is PG / SG?
CREATE TABLE "r" (
  "player" text,
  "nationality" text,
  "jersey_number_s" real,
  "position" text,
  "years" text,
  "from" text
);
SELECT "years" FROM "r" WHERE "nationality"='united states' AND "position"='pg / sg';