How to design the database structure of an online question answering system

How to design the database structure of an online answering system

With the popularization of the Internet and the development of education, more and more students and educational institutions have begun to use online answering systems system for studying and taking exams. A complete online question answering system requires a good database structure to support data storage and management. This article will introduce how to design the database structure of a smaller online question answering system and provide specific code examples.

1. Database design principles

Before designing the database structure, we first need to clarify some database design principles to ensure that the database is efficient, stable and easy to maintain.

(1) Follow the normalization design principles: Under normal circumstances, we should try to follow the normalization design principles and normalize the data into an appropriate paradigm to reduce data redundancy and inconsistency.

(2) Reasonable use of indexes: According to actual query needs, add appropriate indexes to tables in the database to improve query efficiency.

(3) Reasonably divide the table space: For the storage of massive data, you can consider dividing the table space to improve scalability and performance.

2. Database structure design

In this example, we will design a simple online question answering system, including the following main data tables: user table, question table, Question option table and user answer record table. The following is the specific structure and field description of each table.

(1) User table (user)

Fields: user ID (id, primary key), user name (username), password (password), email (email), etc.

Sample code:

CREATE TABLE user (

id INT PRIMARY KEY AUTO_INCREMENT, username VARCHAR(50) NOT NULL, password VARCHAR(50) NOT NULL, email VARCHAR(50) NOT NULL

);

(2) Question table (question)

Field: Question ID (id, primary key), question type (type), question content (content), etc.

Sample code:

CREATE TABLE question (

id INT PRIMARY KEY AUTO_INCREMENT, type INT NOT NULL, content TEXT NOT NULL

);

(3) Question option table (option)

field : Option ID (id, primary key), question ID (question_id, foreign key), option content (content), whether it is correct (is_correct), etc.

Sample code:

CREATE TABLE option (

id INT PRIMARY KEY AUTO_INCREMENT, question_id INT NOT NULL, content TEXT NOT NULL, is_correct INT NOT NULL, FOREIGN KEY (question_id) REFERENCES question(id)

);

(4) User answer record table (record)

Fields: record ID (id, primary key), user ID (user_id, foreign key), question ID (question_id, foreign key), user answer (answer), whether it is correct (is_correct), etc.

Sample code:

CREATE TABLE record (

id INT PRIMARY KEY AUTO_INCREMENT, user_id INT NOT NULL, question_id INT NOT NULL, answer TEXT, is_correct INT NOT NULL, FOREIGN KEY (user_id) REFERENCES user(id), FOREIGN KEY (question_id) REFERENCES question(id)

);

3. Database query example

In In actual use, we often need to perform various query operations to obtain the required data.

(1) Query user answer records

Sample code:

SELECT r.id, u.username, q.content, r.answer, r.is_correct
FROM record r
JOIN user u ON r.user_id = u.id
JOIN question q ON r.question_id = q.id
WHERE u.username = 'user1';

(2) Query the correct answer to the question

Sample code:

SELECT q.id, q.content, o.content
FROM question q
JOIN option o ON q. id = o.question_id
WHERE o.is_correct = 1;

The above is just an example of designing a relatively simple online question answering system database structure. In actual situations, more business requirements may need to be considered. and the relationship between tables. At the same time, we also need to perform performance optimization and security protection based on actual conditions. I hope this article can provide readers with some ideas and guidance on database design for online question answering systems.

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