CREATE TABLE "round_4" (
  "home_team" text,
  "home_team_score" text,
  "away_team" text,
  "away_team_score" text,
  "venue" text,
  "crowd" real,
  "date" text
);

Question: Who is the away side when the crowd is over 18,000 with collingwood at home?
SQL: SELECT "away_team" FROM "round_4" WHERE "crowd">'18,000' AND "home_team"='collingwood';