In the micro-services world, we have the flexibility to choose different DB to every service we build, but how can we know what is the best fit to every use case? We understand that there is a major difference between SQL and NOSQL DB, but there are still so many types for both. How can we know which one we will use for Search, big data, reports, analytics, web application, API apps and more... I will share my experience while building different apps from scratch, and talk about the challenges that I had in choosing the right DB.