如何分別制作DBconnection和Node.js查詢文件

Question

我有問題。 如何連接dbconnection.js和demo_api_select.js在demo_api_select.js上聲明變量時遇到問題。 它不起作用，並顯示如下錯誤提示：

錯誤通知

請幫忙

dbconnection.js：

var mysql=require('mysql');

var con = mysql.createConnection({
  host: "localhost",
  user: "root",
  password: "",
  database: "test"
});

con.connect(function(err) {
  if (err) throw err;
  console.log("Connected!");
});


module.exports = con;

demo_api_select.js

var db = require('./dbconnection');

db.connect(function(err) {
  if (err) throw err;
  //Select all customers and return the result object:
  con.query("SELECT * FROM profil" , function (err, result, fields) {
    if (err) throw err;
    console.log(result);
  });
});

我想使這些代碼和以下代碼一起工作：

var mysql = require('mysql');

var con = mysql.createConnection({
  host: "localhost",
  user: "root",
  password: "",
  database: "test"
});

con.connect(function(err) {
  if (err) throw err;
  //Select all customers and return the result object:
  con.query("SELECT * FROM profil" , function (err, result, fields) {
    if (err) throw err;
    console.log(result);
  });
});

Answer 1

嘗試此代碼。無需兩次連接數據庫

var db = require('./dbconnection');

db.query("SELECT * FROM profil" , function (err, result, fields) {
   if (err) throw err;
    console.log(result);
   });
});