npm install mysql

var mysql   = require('mysql');

var connection = mysql.createConnection({
 host   : 'ip',
 user   : '用户名',
 password : '密码',
 database : 'dbname'
});
connection.connect();

connection.query('SELECT 1 + 1 AS solution', function (error, results, fields) {
 if (error) throw error;
 console.log('The solution is: ', results[0].solution);
});

var mysql = require('mysql');
var pool = mysql.createPool({
 connectionLimit : 连接池数量,
 host      : 'ip地址',
 user      : '账号',
 password    : '密码',
 database    : '数据库名称'
});

//从连接池中获取一个连接
pool.getConnection(function(err, connection) {
  if (err) throw err; // not connected!
 
  // 使用这个连接curd
  connection.query('SELECT something FROM sometable', function (error, results, fields) {
    // 使用完之后，记得把这个连接放到连接池里面去
    connection.release();
 
    // Handle error after the release.
    if (error) throw error;
 
  });
});

query = function (sql, arr, callback) {
  console.log('获取一个连接');
  return new Promise(function (resolve, reject) {
    pool.getConnection(function (err, connection) {
      if (err) {
        reject(err);// not connected!
      } else {
        console.log('开始查询');
        connection.query(sql, arr, function (error, results, fields) {
          connection.release();
          console.log('连接已经释放，返回结果');

          if (error) reject(error);
          // callback && callback(results, fields)
          resolve({
            rows: results,
            fields: fields
          })
        });
      }


    });
  })


}