SQL FOREIGN KEY Constraints

CREATE TABLE buildings (
  building_no int(11) NOT NULL AUTO_INCREMENT,
  building_name varchar(255) NOT NULL,
  address varchar(355) NOT NULL,
  PRIMARY KEY (building_no)
) ENGINE=InnoDB;

 
CREATE TABLE rooms (
  room_no int(11) NOT NULL AUTO_INCREMENT,
  room_name varchar(255) NOT NULL,
  building_no int(11) NOT NULL,
  PRIMARY KEY (room_no),
  KEY building_no (building_no),
  CONSTRAINT rooms_ibfk_1
    FOREIGN KEY (building_no)
    REFERENCES buildings (building_no)
    ON DELETE CASCADE
) ENGINE=InnoDB;