What is the tie when team 2 is koper?
CREATE TABLE "second_round" (
  "tie_no" real,
  "team_1" text,
  "agg" text,
  "team_2" text,
  "1st_leg" text,
  "2nd_leg" text
);
SELECT MIN("tie_no") FROM "second_round" WHERE "team_2"='Koper';