정규화 신경쓰기 (1NF, 2NF, 3NF, BCNF) db create CREATE TABLE subjects ( subjectId INT PRIMARY KEY AUTO_INCREMENT, subjectName VARCHAR(255) NOT NULL, description TEXT, grade INT NOT NULL, semester INT NOT NULL ); CREATE TABLE professors ( professorId INT PRIMARY KEY AUTO_INCREMENT, professorName VARCHAR(255) NOT NULL, email VARCHAR(255), department VARCHAR(255) ); CREATE TABLE topics ( topicId INT PRIMARY KEY AUTO_INCREMENT, subjectId INT, topicTitle VARCHAR(255) NOT NULL, topicOrder INT NOT NULL, description TEXT, FOREIGN KEY (subjectId) REFERENCES subjects(subjectId) ); CREATE TABLE subtopics ( subtopicId INT PRIMARY KEY AUTO_INCREMENT, topicId INT, subtopicTitle VARCHAR(255) NOT NULL, subtopicOrder INT NOT NULL, description TEXT, FOREIGN KEY (topicId) REFERENCES topics(topicId) ); CREATE TABLE detailedTopics ( detailedTopicId INT PRIMARY KEY AUTO_INCREMENT, subtopicId INT, detailedTopicTitle VARCHAR(255) NOT NULL, detailedTopicOrder INT NOT NULL, description TEXT, FOREIGN KEY (subtopicId) REFERENCES subtopics(subtopicId) );