Entity relationship diagram analysis in the MySQL table structure design of the online examination system

Entity relationship diagram analysis in the MySQL table structure design of the online examination system requires specific code examples

When designing the MySQL table structure of the online examination system, it is necessary Consider the entities in the system and the relationships between them. A reasonable table structure design can effectively support system functions and improve system performance and maintainability. This article will introduce the entity relationship diagram analysis in the MySQL table structure design of the online examination system and provide some specific code examples.

Online examination systems usually include the following entities: users, exams, test questions, answer sheets and scores. Let's analyze the relationships between these entities one by one.

1. User entity: User entity represents user information in the system. Users can be students, teachers, or administrators. In the database, you can create a table named "users" to store user information.

CREATE TABLE users (
    id INT PRIMARY KEY AUTO_INCREMENT,
    name VARCHAR(50) NOT NULL,
    email VARCHAR(50) UNIQUE,
    password VARCHAR(100) NOT NULL,
    role ENUM('student', 'teacher', 'admin') NOT NULL
);

2. Exam entity: Exam entity represents the exam information in the system. An exam can contain multiple questions. In the database, you can create a table named "exams" to store exam information.

CREATE TABLE exams (
    id INT PRIMARY KEY AUTO_INCREMENT,
    title VARCHAR(100) NOT NULL,
    description VARCHAR(500),
    start_time DATETIME NOT NULL,
    end_time DATETIME NOT NULL
);

3. Test question entity: The question entity represents the question information in the system. An exam can contain multiple questions. In the database, you can create a table named "questions" to store test question information.

CREATE TABLE questions (
    id INT PRIMARY KEY AUTO_INCREMENT,
    exam_id INT NOT NULL,
    question_text VARCHAR(500) NOT NULL,
    is_multiple_choice BOOLEAN NOT NULL,
    -- 添加其他字段，如选项、正确答案等
    FOREIGN KEY (exam_id) REFERENCES exams(id)
);

4. Answer sheet entity: The answer sheet entity represents the user's answer information. A user can have multiple answer records. In the database, you can create a table named "answers" to store answer sheet information.

CREATE TABLE answers (
    id INT PRIMARY KEY AUTO_INCREMENT,
    user_id INT NOT NULL,
    exam_id INT NOT NULL,
    question_id INT NOT NULL,
    answer_text VARCHAR(500) NOT NULL,
    FOREIGN KEY (user_id) REFERENCES users(id),
    FOREIGN KEY (exam_id) REFERENCES exams(id),
    FOREIGN KEY (question_id) REFERENCES questions(id)
);

5. Score entity: Score entity represents the user’s test score information. A user can take multiple exams, and each exam has a score. In the database, you can create a table named "scores" to store score information.

CREATE TABLE scores (
    id INT PRIMARY KEY AUTO_INCREMENT,
    user_id INT NOT NULL,
    exam_id INT NOT NULL,
    score DECIMAL(5,2) NOT NULL,
    FOREIGN KEY (user_id) REFERENCES users(id),
    FOREIGN KEY (exam_id) REFERENCES exams(id)
);

The above is the analysis of the entity relationship diagram in the MySQL table structure design of the online examination system, and specific code examples are given. Through reasonable table structure design, we can easily store and query user information, exam information, test question information, answer sheet information, and score information. Such a design can improve the performance and maintainability of the system, making the online examination system more stable and efficient.

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