module.exports = {
    'connection': {
        'host': '127.0.0.1', // local or ip adress .
        'user': 'root', // mysql user name
        'password': 'password', // password 
        'database': 'dbname'// database name .
    },
	'database': 'dbname',
};

CREATE TABLE `users` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(100) DEFAULT NULL,
  `password` varchar(100) DEFAULT NULL,
  `verification` tinyint(1) DEFAULT '0',
  `code` varchar(100) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=latin1;

    app.post("/email",isLoggedIn,function(req,res){
    console.log(req.body);
    var row=[];
    var code="";
    var email="";
    connection.query('select * from users where id = ?',[req.user.id], function (err, rows) {
        if (err) {
            console.log(err);
        } else {
            if (rows.length) {
                for (var i = 0, len = rows.length; i < len; i++) {  //query den gelen bütün parametreleri rows sınıfına ekliyoruz .
                    row[i] = rows[i];
                    code =  bcrypt.hashSync(rows[i].username, null, null)
                    console.log(rows[i].username);
                    console.log(code);
                    email = rows[i].username;
                    
                }  
            }
            console.log(row);
            
        }

        connection.query("UPDATE users SET code='"+code+"' WHERE id='"+req.user.id+"'");
        sendMail(email,code);
    });
    

});


mail function

function sendMail(mail_adress,code){
var mail=mail_adress;
var code=code;

console.log(mail,code);

var nodemailer = require('nodemailer');
var transporter = nodemailer.createTransport({
  service: 'gmail',
  auth: {
    user: '[email protected]',
    pass: 'your_gmail_pass'
  }
});
var mailOptions = {
  from: 'from_gmail_adres',
  to: mail,
  subject: 'click this button',
  text: 'That was easy!',

  html: " <a href='http://127.0.0.1/verification/"+code+"'> http://127.0.0.1/verification/"+code+"  </a> "
};

transporter.sendMail(mailOptions, function(error, info){
  if (error) {
    console.log(error);
  } else {
    console.log('Email sent: ' + info.response);
  }
});

}

verification code 

    app.get("/verification/:code",isLoggedIn,function(req,res){
        console.log("burda");
        var code = req.params.code;
        var row = [];
    connection.query('select * from users where code = ?',[code], function (err, rows) {
        if (err) {
            console.log(err);
        } else {
            if (rows.length) {
                connection.query("UPDATE users set verification = '"+1+"' where code = '"+code+"'");
                res.redirect("/");
            }
            else{
                res.redirect("/error");
            }
            console.log(row);
            
        }

       
    });
});


index.ejs scripts

$(document).ready(function(){
        $('#sendemail').click(function(){
        $("#sendemail").hide();
        var data = {};
        data.userID = '<%=rows.id%>';
        $.ajax({
            url: '/email',
            type: 'POST',
            contentType: 'application/json',
            data: JSON.stringify(data),
            success: function(data) {
                console.log(data);
            }
        });
    });
});