javascript mysql数据库

const mysql = require('mysql');

const connection = mysql.createConnection({
  host: 'localhost',
  user: 'user',
  password: 'password',
  database: 'database_name'
});

connection.connect((err) => {
  if (err) throw err;
  console.log('Connected to MySQL database!');
});

connection.query('SELECT * FROM table_name', (err, results, fields) => {
  if (err) throw err;
  console.log(results);
});

connection.on('error', (err) => {
  console.error('Database connection error:', err);
  if (err.code === 'PROTOCOL_CONNECTION_LOST') {
    console.error('Database connection was closed.');
  }
  if (err.code === 'ER_CON_COUNT_ERROR') {
    console.error('Database has too many connections.');
  }
  if (err.code === 'ECONNREFUSED') {
    console.error('Database connection was refused.');
  }
});