app.js

const connection = require('./knex/MySQL');

var checkUser = conncetion.userExists("226018734496546817")

if (checkUser == 1) {
 console.log("User exists");
else {
  connection.createUser({
    name: "Thomas Strømme",
    id: "226018734496546817"
  });
}

knex.js

const environment = process.env.ENVIRONMENT || 'development'
const config = require('../knexfile.js')[environment];
module.exports = require('knex')(config);

knexfile.js

module.exports = {
  development: {
    client: 'mysql',
    connection: {
      user: 'root',
      password: '',
      database: 'facebookdiscordrole',
      charset: 'utf8'
    },
    acquireConnectionTimeout: 4000,
    migrations: {
      directory: __dirname + '/knex/migrations',
    },
    seeds: {
      directory: __dirname + '/knex/seeds'
    }
  },
  production: {
    client: 'mysql',
    connection: {
      database: 'facebookdiscordrole',
      user:     'root',
      password: '',
      charset: 'utf8'
    },
    pool: {
      min: 2,
      max: 10
    },
    migrations: {
      tableName: 'knex_migrations'
    }
  }
};

mysql.js

userExists (id) {
		// console.log(`User ${discord_id} already exists`)
		return knex('user')
		  .count('discord_id')
			.where('discord_id', + id)
			.limit(1)
			.then((rows) => {
				if (rows.length === 0) { return 0;}
				else { return 1 };
			})
			.catch((err) => {
				console.log(err);
			})
	    .finally(() => {
	      knex.destroy();
	    })
  }