How to develop a simple examination system using MySQL and C++

How to use MySQL and C to develop a simple examination system

Currently, in the field of education, the demand for electronic examination systems is increasing. This article will introduce how to use MySQL and C to develop a simple examination system. Through this system, teachers can create question banks and generate test papers, and students can log in to the system to take exams and automatically score them.

1. MySQL database design
   First, we need to design a MySQL database to store question bank, student information, test papers and other data. The following is a simple database design example:

• Question table (questions): contains fields such as questions, options, answers, etc.
  CREATE TABLE questions (
  id INT PRIMARY KEY AUTO_INCREMENT,
  question VARCHAR(255) NOT NULL,
  options TEXT,
  answer VARCHAR(255) NOT NULL
  );
• Students table (students): Contains fields such as student name (name), student number (student_id).
  CREATE TABLE students (
  id INT PRIMARY KEY AUTO_INCREMENT,
  name VARCHAR(255) NOT NULL,
  student_id VARCHAR(255) NOT NULL
  );
• Exam table (exams): Contains fields such as the name of the test paper (name), the teacher to whom it belongs (teacher_id).
  CREATE TABLE exams (
  id INT PRIMARY KEY AUTO_INCREMENT,
  name VARCHAR(255) NOT NULL,
  teacher_id INT NOT NULL
  );
• Exam answer sheet (responses ): Contains fields such as students participating in the exam (student_id), corresponding test paper (exam_id), and answer status (choices).
  CREATE TABLE responses (
  id INT PRIMARY KEY AUTO_INCREMENT,
  student_id INT NOT NULL,
  exam_id INT NOT NULL,
  choices TEXT,
  score FLOAT(2, 1)
  );

2. C Development
   In C development, we need to use the MySQL C Connector to connect to the MySQL database. The following is a simple C code example:

#include <mysql_driver.h>
#include <mysql_connection.h>

using namespace std;
using namespace sql;

int main() {
  sql::mysql::MySQL_Driver *driver;
  sql::Connection *con;

  driver = sql::mysql::get_mysql_driver_instance();
  con = driver->connect("tcp://127.0.0.1:3306", "root", "password");

  con->setSchema("exam_system");

  // 进行数据库操作

  delete con;

  return 0;
}

In this code, we first introduced the two header files mysql_driver.h and mysql_connection.h. Then, obtain the MySQL driver instance through the get_mysql_driver_instance() function and connect to the database using the connect() function. Next, select the database to use through the setSchema() function. Finally, release the connection after performing database operations.

3. Implementing the functions of the examination system
   To implement the functions of the examination system in C, we need to write some functions to implement functions such as question bank operation, test paper generation, examination answering and automatic scoring. The following is a simple code example:

#include <iostream>
#include <string>
#include <vector>
#include <mysql_driver.h>
#include <mysql_connection.h>

using namespace std;
using namespace sql;

class ExamSystem {
private:
  sql::mysql::MySQL_Driver *driver;
  sql::Connection *con;

public:
  ExamSystem() {
    driver = sql::mysql::get_mysql_driver_instance();
    con = driver->connect("tcp://127.0.0.1:3306", "root", "password");
    con->setSchema("exam_system");
  }

  ~ExamSystem() {
    delete con;
  }

  vector<string> getQuestions() {
    vector<string> questions;

    // 查询题库表，获取题目和选项
    sql::Statement *stmt;
    sql::ResultSet *res;

    stmt = con->createStatement();
    res = stmt->executeQuery("SELECT question, options FROM questions");

    while (res->next()) {
      string question = res->getString("question");
      string options = res->getString("options");
      // 将题目和选项拼接成一个字符串并添加到vector中
      questions.push_back(question + "
" + options);
    }

    delete res;
    delete stmt;

    return questions;
  }

  void generateExam(string name) {
    // 生成试卷并插入考试表
    sql::Statement *stmt;

    stmt = con->createStatement();
    stmt->execute("INSERT INTO exams (name, teacher_id) VALUES ('" + name + "', 1)");

    delete stmt;
  }

  void submitResponse(int student_id, int exam_id, vector<string> choices) {
    // 将考试答卷插入答卷表
    sql::Statement *stmt;

    stmt = con->createStatement();
    stmt->execute("INSERT INTO responses (student_id, exam_id, choices) VALUES (" + to_string(student_id) + ", " + to_string(exam_id) + ", '" + choices + "')");

    delete stmt;
  }

  float calculateScore(int student_id, int exam_id) {
    float score = 0;

    // 查询答卷表，计算得分
    sql::Statement *stmt;
    sql::ResultSet *res;

    stmt = con->createStatement();
    res = stmt->executeQuery("SELECT choices FROM responses WHERE student_id = " + to_string(student_id) + " AND exam_id = " + to_string(exam_id));

    string choices;
    if (res->next()) {
      choices = res->getString("choices");
    }

    // 根据题目和答案的对应关系计算得分

    delete res;
    delete stmt;

    return score;
  }
};

int main() {
  ExamSystem examSystem;
  vector<string> questions = examSystem.getQuestions();
  
  // 输出题目和选项

  return 0;
}

In this example, we construct an ExamSystem class to implement the functions of the exam system. In the constructor, we connect to the MySQL database and select the database to use. The getQuestions() function is used to query the question bank table and obtain questions and options, and generate a vector containing questions and options. The generateExam() function is used to generate test papers and insert them into the test table. The submitResponse() function is used to insert the exam answer sheet into the answer sheet. The calculateScore() function is used to calculate the score based on the answer sheet.

In the main function, we use the functions of the examination system by calling the functions of the ExamSystem class.

Summary:
This article introduces how to use MySQL and C to develop a simple examination system. The question bank, student information, test papers and other data are stored through the MySQL database, and functions such as question bank operation, test paper generation, examination answering and automatic scoring are implemented using codes written in C. Developers can expand and optimize the code according to specific needs to implement more complex examination systems.

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