What are the key differences between SQL and NoSQL databases, and in what scenarios would you choose one over the other?

In my final year of college, I worked on a project to design a database for a library management system. We chose SQL because we needed to maintain complex relationships between books, authors, and borrowers. Using SQL allowed us to enforce data integrity and perform complex queries to track which books were borrowed or available. This experience taught me the importance of using relational databases for structured data and complex queries, which is often necessary in educational and administrative applications.

During my time volunteering for a local non-profit, I helped manage event registrations using a NoSQL database. We used MongoDB to store participant information because we expected a large number of registrations and needed to adapt quickly to changing event details. The flexibility of NoSQL allowed us to store varied data types without strict schema requirements, making it easier to update and retrieve information efficiently. This experience highlighted how NoSQL can be beneficial for dynamic applications that require speed and flexibility.

In my first job as a junior developer at an e-commerce startup, I was involved in a project that required handling vast amounts of user data and product listings. We opted for a hybrid approach, using SQL for transactional data like orders and NoSQL for user activity logs. This dual strategy allowed us to leverage the strengths of both databases—SQL for reliable transactions and NoSQL for scalability. This taught me how to choose the right database based on specific application needs, balancing reliability with performance.