答案是设计在线考试系统数据库需明确用户、科目、试题、试卷、考试记录等核心模块,通过MySQL建立users、subjects、questions、options、exams、exam_questions、exam_attempts和user_answers等表,利用外键约束保证数据完整性,采用JSON字段灵活存储多选答案,结合索引优化查询效率,并通过角色权限、密码加密和时间控制确保安全性与流程可控。

开发一个在线考试系统的数据库,关键在于合理设计表结构,确保数据完整性、可扩展性和查询效率。MySQL 是一个成熟的关系型数据库,非常适合这类应用。以下是构建在线考试系统数据库的核心设计思路和实现方法。
在线考试系统通常包含以下主要功能模块:
根据功能需求,建立以下核心表:
用户表(users)
CREATE TABLE users (
user_id INT AUTO_INCREMENT PRIMARY KEY,
username VARCHAR(50) UNIQUE NOT NULL,
password CHAR(64) NOT NULL, -- 推荐使用SHA-256加密
role ENUM('student', 'teacher', 'admin') NOT NULL,
name VARCHAR(100),
email VARCHAR(100),
created_at DATETIME DEFAULT CURRENT_TIMESTAMP
);
科目表(subjects)
CREATE TABLE subjects ( subject_id INT AUTO_INCREMENT PRIMARY KEY, subject_name VARCHAR(100) NOT NULL, description TEXT );
试题表(questions)
CREATE TABLE questions (
question_id INT AUTO_INCREMENT PRIMARY KEY,
subject_id INT,
question_text TEXT NOT NULL,
question_type ENUM('single', 'multiple', 'judgment') NOT NULL,
difficulty ENUM('easy', 'medium', 'hard'),
creator_id INT, -- 出题教师ID
created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
FOREIGN KEY (subject_id) REFERENCES subjects(subject_id),
FOREIGN KEY (creator_id) REFERENCES users(user_id)
);
选项表(options)
CREATE TABLE options ( option_id INT AUTO_INCREMENT PRIMARY KEY, question_id INT, option_label CHAR(1), -- A, B, C, D option_text TEXT NOT NULL, is_correct BOOLEAN DEFAULT FALSE, FOREIGN KEY (question_id) REFERENCES questions(question_id) ON DELETE CASCADE );
试卷表(exams)
CREATE TABLE exams ( exam_id INT AUTO_INCREMENT PRIMARY KEY, exam_name VARCHAR(100) NOT NULL, subject_id INT, total_questions INT, duration_minutes INT, -- 考试时长 created_by INT, created_at DATETIME DEFAULT CURRENT_TIMESTAMP, FOREIGN KEY (subject_id) REFERENCES subjects(subject_id), FOREIGN KEY (created_by) REFERENCES users(user_id) );
试卷题目关联表(exam_questions)
CREATE TABLE exam_questions ( exam_id INT, question_id INT, PRIMARY KEY (exam_id, question_id), FOREIGN KEY (exam_id) REFERENCES exams(exam_id) ON DELETE CASCADE, FOREIGN KEY (question_id) REFERENCES questions(question_id) );
考试记录表(exam_attempts)
CREATE TABLE exam_attempts (
attempt_id INT AUTO_INCREMENT PRIMARY KEY,
user_id INT,
exam_id INT,
start_time DATETIME DEFAULT CURRENT_TIMESTAMP,
end_time DATETIME,
status ENUM('ongoing', 'submitted', 'timeout'),
score DECIMAL(5,2),
FOREIGN KEY (user_id) REFERENCES users(user_id),
FOREIGN KEY (exam_id) REFERENCES exams(exam_id)
);
学生答案表(user_answers)
CREATE TABLE user_answers ( answer_id INT AUTO_INCREMENT PRIMARY KEY, attempt_id INT, question_id INT, selected_options JSON, -- 存储选择的选项如 ["A","C"] answered_at DATETIME DEFAULT CURRENT_TIMESTAMP, FOREIGN KEY (attempt_id) REFERENCES exam_attempts(attempt_id) ON DELETE CASCADE );
使用外键约束:确保数据一致性,比如删除科目时自动处理相关试题。
灵活存储答案:使用 JSON 字段保存多选项答案,适应不同题型。
索引优化:在常用查询字段上建立索引,如 user_id、exam_id、question_id。
安全性考虑:密码必须加密存储,推荐使用 SHA-256 或 bcrypt。
时间控制逻辑:exam_attempts 表中的 start_time 和 duration 可用于判断是否超时。
获取某次考试的所有题目及选项:
SELECT q.question_text, o.option_label, o.option_text, o.is_correct FROM exam_questions eq JOIN questions q ON eq.question_id = q.question_id JOIN options o ON q.question_id = o.question_id WHERE eq.exam_id = 1 ORDER BY q.question_id, o.option_label;
计算考生成绩:
SELECT SUM(CASE WHEN ua.selected_options = (SELECT JSON_ARRAYAGG(option_label) FROM options WHERE question_id = ua.question_id AND is_correct = 1) THEN 1 ELSE 0 END) AS correct_count FROM user_answers ua WHERE ua.attempt_id = 1;
基本上就这些。设计清晰、关系明确,后续配合后端逻辑就能支撑完整的在线考试流程。不复杂但容易忽略细节,比如外键级联和状态管理。
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