先做個總結：連線資料庫是一個建庫，建Schema的過程...之後就是利用例項化的物件進行資料庫的操作...

1.moogoDB的連線

//database.js
var mongoose = require('mongoose')
mongoose.connect('mongodb://localhost:27017/lagou', {
  useNewUrlParser: true
})

var db = mongoose.connection
db.on('error', console.error.bind(console, 'connection error:'))
db.once('open', function () {
  // we're connected!
})

module.exports = mongoose
 

//某一個model的程式碼
const mongoose = require('../utils/database')

// 建立Schema，建立集合
const positionSchema = new mongoose.Schema({
  companyLogo: String,
  companyName: String,
  positionName: String,
  city: String,
  salary: String,
  createDate: String
})
const PositionModel = mongoose.model('positions', positionSchema)
//之後進行一些增刪改查的操作
 

2.mysql的連線

//連線資料庫
var mysql      = require('mysql');
var connection = mysql.createPool({
  connectionLimit : 10,
  host     : 'localhost',
  user     : 'root',
  password : '',
  database : 'gp7'
});
 //然後做增刪改查的工作
//查
const _select = (sql) => {
  return new Promise((resolve, reject) => {
    connection.query('SELECT * FROM posts')//暫定查所有
      .on('error', (err) => {
        reject(err.message)
      })
      .on('result', (row) => {
        resolve(row)
      })
  })
}
 

詳細的查詢資料庫的方法

moogoose

https://mongoosejs.com/docs/guide.html

mysql

https://www.npmjs.com/package/mysql