Customers List (MySQL - Connection One-by-One using Promises)

This section implement a MySQL Database connected with node.js mysql driver creating and managing connections one-by-one using Promises. Dynamic web pages without connection pooling open connections to database services as required and close them when the page is done servicing a particular request. Opening and maintaining a database connection for each user is costly and wastes resources. In this section every database calls are closed after completing. In addition the calls are write with asynchronous code using Promises.