CREATE TABLE `agenda` (
  `student_id` int(11) NOT NULL,
  `subject_id` int(11) NOT NULL,
  PRIMARY KEY (`student_id`,`subject_id`),
  KEY `fk_subject_idx` (`subject_id`),
  CONSTRAINT `fk_student_agenda` FOREIGN KEY (`student_id`) REFERENCES `students` (`student_id`),
  CONSTRAINT `fk_subject` FOREIGN KEY (`subject_id`) REFERENCES `subjects` (`subject_id`)
);

CREATE TABLE `majors` (
  `major_id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(50) DEFAULT NULL,
  PRIMARY KEY (`major_id`)
);

CREATE TABLE `payments` (
  `payment_id` int(11) NOT NULL AUTO_INCREMENT,
  `payment_date` date DEFAULT NULL,
  `payment_amount` decimal(8,2) DEFAULT NULL,
  `student_id` int(11) DEFAULT NULL,
  PRIMARY KEY (`payment_id`),
  KEY `FK_STUDENTS_idx` (`student_id`),
  CONSTRAINT `FK_STUDENTS` FOREIGN KEY (`student_id`) REFERENCES `students` (`student_id`)
);

CREATE TABLE `students` (
  `student_id` int(11) NOT NULL AUTO_INCREMENT,
  `student_number` varchar(12) DEFAULT NULL,
  `student_name` varchar(50) DEFAULT NULL,
  `major_id` int(11) DEFAULT NULL,
  PRIMARY KEY (`student_id`),
  KEY `fk_majors_idx` (`major_id`),
  CONSTRAINT `fk_majors` FOREIGN KEY (`major_id`) REFERENCES `majors` (`major_id`)
);

CREATE TABLE `subjects` (
  `subject_id` int(11) NOT NULL AUTO_INCREMENT,
  `subject_name` varchar(50) DEFAULT NULL,
  PRIMARY KEY (`subject_id`)
);