Table: f1_race_results_4
Columns: rd
grand_prix
pole_position
fastest_lap
winning_driver
constructor
report

Question: What was the constructor in the Belgian Grand Prix round?
SQL: SELECT "constructor" FROM f1_race_results_4 WHERE "grand_prix" = 'Belgian Grand Prix'

Question: Who had the fastest lap in round 15?
SQL: SELECT "fastest_lap" FROM f1_race_results_4 WHERE "rd" = 15