CREATE TABLE "fourth_round_proper" (
  "tie_no" text,
  "home_team" text,
  "score" text,
  "away_team" text,
  "date" text
);

Question: What is the date when tie number is 6?
SQL: SELECT "date" FROM "fourth_round_proper" WHERE "tie_no"='6';

Question: Who is the home team with tie number 9?
SQL: SELECT "home_team" FROM "fourth_round_proper" WHERE "tie_no"='9';

Question: Who is the home team when Sheffield United is the away team?
SQL: SELECT "home_team" FROM "fourth_round_proper" WHERE "away_team"='sheffield united';

Question: What is the date when Aston Villa is the away team?
SQL: SELECT "date" FROM "fourth_round_proper" WHERE "away_team"='aston villa';

Question: Who is the home team on 31 January 1951 when away team was Sheffield United?
SQL: SELECT "home_team" FROM "fourth_round_proper" WHERE "date"='31 january 1951' AND "away_team"='sheffield united';