CREATE TABLE "round_21" (
  "home_team" text,
  "home_team_score" text,
  "away_team" text,
  "away_team_score" text,
  "venue" text,
  "crowd" real,
  "date" text
);

Question: How big was the crowd size, at the Junction Oval venue?
SQL: SELECT SUM("crowd") FROM "round_21" WHERE "venue"='junction oval';

Question: What is the visiting team of Melbourne's score?
SQL: SELECT "away_team_score" FROM "round_21" WHERE "away_team"='melbourne';

Question: What is the average crowd size of Fitzroy's home team?
SQL: SELECT AVG("crowd") FROM "round_21" WHERE "home_team"='fitzroy';