41. 在 SQL 中，如何定義一個觸發器？ (A) CREATE TRIGGER trigger_name ON table_name BEFORE INSERT AS BEGIN ... END； (B) CREATE TRIGGER trigger_name ON table_name FOR EACH ROW BEGIN ... END； (C) CREATE TRIGGER trigger_name ON table_name AFTER INSERT AS BEGIN ... END； (D) CREATE TRIGGER trigger_name ON table_name FOR EACH STATEMENT BEGIN ... END；。