Which Set 2 has a Date of 25 may, and a Set 3 of 21–25?
CREATE TABLE "pool_a" (
  "date" text,
  "score" text,
  "set_1" text,
  "set_2" text,
  "set_3" text,
  "total" text
);
SELECT "set_2" FROM "pool_a" WHERE "date"='25 may' AND "set_3"='21–25';