ដើម្បីជ្រើសរើសយក​ទិន្នន័យ​ដ៏ជាក់លាក់ណាមួយចំនួន យើងចាបាច់​ត្រូវ​ប្រើបញ្ជា «SELECT» រួម​ជាមួយ​នឹង​បញ្ជា «WHERE» នៃ​ភាសា SQL ដោយ​ធ្វើ​ដូច​ខាង​ក្រោម​នេះ៖

import express from 'express'
import path from 'path'

const app = express()
const port = process.env.PORT || 3000
const __dirname = path.resolve()
 
import index from './routes/index.js'
import backend from './routes/backend.js'
import con from './models/connectMySQL.js'

app.use('/',function(req,res,next){
    req.con = con
    req.__dirname = __dirname
    next()
})

app.set('views', path.join(__dirname, 'views'))
app.set('view engine', 'ejs')
app.use(express.static(path.join(__dirname, 'public')))
app.use(express.urlencoded({extended:false}))
app.use(express.json())
                                  
app.use('/',index) 
app.use('/backend',backend) 

app.listen(port,function(){
    console.log(`This application is listening to the port: ${port}`)
})

/* ./routes/index.js */
import express from 'express'
import selectData from '../models/mysql.js'
const index = express.Router()

index.use(selectData)

index.get('/',(req,res)=>{
    res.render('base',req.data)
})
 
export default index

//models/mysql.js

function selectData(req,res,next){
    let sql = `SELECT * FROM users WHERE username = 'Tin Niroth'`
    req.con.query(sql,function(err,result){
        if(err) throw err
        req.data = {}
        req.data.message = JSON.stringify(result)
        next()
    })
}

export default selectData