SQL vs NoSQL
I have heard many people say that SQL databases are for structured data and NoSQL for unstructured data. In a sense, that is certainly true, because you can store nearly everything and anything in a NoSQL database. There is no need for a detailed pre-planning of the data structure when implementing a NoSQL database. On the other hand, with a SQL database you need to plan out the data you will store and how that will fit into tables.
Another big question to ask when choosing between these two is: “Will there be any relationships between sets of data?”. The strength of SQL databases is in the relationships that you can define between tables. These relationships are usually either one-to-many or many-to-many. That allows you to query for all sorts of data that have some relation to one another. With NoSQL, the whole relation business does not apply as much. Hence, why people regard it as a solution for unstructured data.