CREATE TABLE "calendar" (
  "round" text,
  "main_date" text,
  "number_of_fixtures" real,
  "clubs" text,
  "new_entries_this_round" text
);

Question: What is the Clubs when there are 4 for the number of fixtures?
SQL: SELECT "clubs" FROM "calendar" WHERE "number_of_fixtures"=4;

Question: What is the sum of Number of fixtures when the rounds shows quarter-finals?
SQL: SELECT SUM("number_of_fixtures") FROM "calendar" WHERE "round"='quarter-finals';

Question: What is the New entries this round when the round is the semi-finals?
SQL: SELECT "new_entries_this_round" FROM "calendar" WHERE "round"='semi-finals';

Question: What is the Round when the number of fixtures is more than 2, and the Main date of 7 and 28 november 2007?
SQL: SELECT "round" FROM "calendar" WHERE "number_of_fixtures">2 AND "main_date"='7 and 28 november 2007';