Question: What is the Clubs when there are 4 for the number of fixtures?
SQL: SELECT "Clubs" FROM "2-15488604-1" WHERE "Number of fixtures" = 4.0;

Question: What is the sum of Number of fixtures when the rounds shows Quarter-finals?
SQL: SELECT SUM("Number of fixtures") FROM "2-15488604-1" 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 "2-15488604-1" 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 "2-15488604-1" WHERE "Number of fixtures" > 2.0 AND "Main date" = '7 and 28 November 2007';