What is Team 2 if the 1st Leg is 3-1 and the 2nd Leg is 4-1?
CREATE TABLE "round_16_matches" (
  "team_1" text,
  "agg" text,
  "team_2" text,
  "1st_leg" text,
  "2nd_leg" text
);
SELECT "team_2" FROM "round_16_matches" WHERE "1st_leg"='3-1' AND "2nd_leg"='4-1';