MySQL
MySQL is globally renowned for being the most secure and reliable database management system used in popular web applications like WordPress, Drupal, Joomla, Facebook and Twitter. The data security and support for transactional processing that accompany the recent version of MySQL, can greatly benefit any business especially if it is an eCommerce business that involves frequent money transfers. MySQL is designed to meet even the most demanding applications while ensuring optimum speed, full-text indexes and unique memory caches for enhanced performance.
MongoDB
MongoDB’s document model allows virtually any kind of data structure to be modeled and manipulated easily. MongoDB’s BSON data format, inspired by JSON, allows you to have objects in one collection have different sets of fields. Most databases force you to use heavy wrappers, like ORMs (Object Relational Mappers), to get data into Object form for use in programs. MongoDB’s decision to store and represent data in a document format means that you can access it from any language, in data structures that are native to that language