Send SQL statement to MySQL

sql-query.js

// This file does only one thing it can not call on other functions 

const mysql = require('mysql');
const connection = mysql.createConnection({
    host : process.env.MYSQL_HOST,
    user : process.env.MYSQL_USER,
    password : process.env.MYSQL_PASSWORD,
    database : process.env.MYSQL_DATABASE
});

exports.query = (SQLstatement) => {
    return new Promise((resolve, reject) => {
        if(SQLstatement){
            connection.connect((err) => {
                if(err){
                    reject(Error(err))
                } else {
                    connection.query(SQLstatement, (error, results, fields) => {
                        resolve(results)
                        connection.end(function(err) {
                            if (err) {
                                reject(Error(err))
                            }
                        });
                    });
                }
            })
        } else (
            reject(Error('No SQL statement provided'))
        )
    })
}