How to connect node.js to MySQL

This time I will bring you node.jsHow to connect to MySQL, what are the precautions for node.js to connect to MySQL, the following is a practical case, let’s take a look one time.

The example in this article describes the connection MySQL database function implemented by nodejs. Share it with everyone for your reference, the details are as follows:

1. Run npm install mysql in the project directory to install the mysql module for nodejs;

2. Create the db.js module to connect to mysql and define the query query method;

var mysql = require('mysql');
// 创建一个数据库连接池
var pool = mysql.createPool({
 connectionLimit: 50,
 host: 'localhost',
 user: 'admin',
 password: '123456',
 database: 'rp-test'
});
// SELECT * FROM users
// 让我们的方法支持两种模式
// 一种是只传入SQL语句和回调函数
// 一种是传入SQL语句、参数数据、回调函数
exports.query = function (sql, P, C) {
 var params = [];
 var callback;
 // 如果用户传入了两个参数，就是SQL和callback
 if (arguments.length == 2 && typeof arguments[1] == 'function') {
  callback = P;
 } else if (arguments.length == 3 && Array.isArray(arguments[1]) && typeof arguments[2] == 'function') {
  params = P;
  callback = C;
 } else {
  throw new Error('对不起，参数个数不匹配或者参数类型错误');
 }
 // 如果用户传入了三个参数，那么就是SQL和参数数组、回调函数
 // 从池子里面拿一个可以使用的连接
 pool.getConnection(function (err, connection) {
  // Use the connection
  connection.query(sql, params, function () {
   // 使用完毕之后，将该连接释放回连接池
   connection.release();
   callback.apply(null, arguments);
  });
 });
};

3. Query example

var express = require('express');
var db = require('./db');
var router = express.Router();
router.get('/',function(req, res, next){
  db.query("select * from app",function(err,result){
     //console.log(result);
    res.send(JSON.stringify (result));
  });
});
module.exports=router;

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the php Chinese website!

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