MySQL と JavaScript を使用して簡単なデータ分析機能を実装する方法

CREATE DATABASE data_analysis;
USE data_analysis;

CREATE TABLE student_scores (
  id INT AUTO_INCREMENT PRIMARY KEY,
  name VARCHAR(50),
  subject VARCHAR(50),
  score INT
);

INSERT INTO student_scores (name, subject, score) VALUES ('John', 'Math', 80);
INSERT INTO student_scores (name, subject, score) VALUES ('John', 'English', 90);
INSERT INTO student_scores (name, subject, score) VALUES ('John', 'Science', 70);
INSERT INTO student_scores (name, subject, score) VALUES ('Alice', 'Math', 85);
INSERT INTO student_scores (name, subject, score) VALUES ('Alice', 'English', 95);
INSERT INTO student_scores (name, subject, score) VALUES ('Alice', 'Science', 75);
INSERT INTO student_scores (name, subject, score) VALUES ('Bob', 'Math', 75);
INSERT INTO student_scores (name, subject, score) VALUES ('Bob', 'English', 80);
INSERT INTO student_scores (name, subject, score) VALUES ('Bob', 'Science', 85);

// 引入MySQL的JavaScript库
const mysql = require('mysql');

// 创建一个连接对象
const connection = mysql.createConnection({
  host: 'localhost',
  user: 'root',
  password: 'password',
  database: 'data_analysis'
});

// 连接数据库
connection.connect();

// 查询数据
connection.query('SELECT * FROM student_scores', function (error, results, fields) {
  if (error) throw error;

  // 对查询结果进行分析
  // ...

  // 关闭数据库连接
  connection.end();
});

// 查询数据
connection.query('SELECT * FROM student_scores', function (error, results, fields) {
  if (error) throw error;

  // 计算每个学生的平均成绩
  const students = {};
  results.forEach(function (row) {
    if (!(row.name in students)) {
      students[row.name] = {
        total: 0,
        count: 0
      };
    }
    students[row.name].total += row.score;
    students[row.name].count++;
  });

  // 打印每个学生的平均成绩
  for (const name in students) {
    const average = students[name].total / students[name].count;
    console.log(`${name}: ${average}`);
  }

  // 关闭数据库连接
  connection.end();
});