CREATE TABLE "round_of_16" (
  "date" text,
  "score" text,
  "set_1" text,
  "set_2" text,
  "total" text
);

Question: What is the score for Set 2 at 15:21?
SQL: SELECT "score" FROM "round_of_16" WHERE "set_2"='15:21';

Question: What Set 2 has a set one at 19:21?
SQL: SELECT "set_2" FROM "round_of_16" WHERE "set_1"='19:21';

Question: What is the score for Set 1 at 19:21?
SQL: SELECT "score" FROM "round_of_16" WHERE "set_1"='19:21';

Question: What is the Set 1 with set 2 at 21:17?
SQL: SELECT "set_1" FROM "round_of_16" WHERE "set_2"='21:17';