Meets ACID requirements
They have a simple structure
They use SQL and allow you to quickly update data
Minuses
It can take a long time to execute a query because each query refers to a table and the larger the table, the longer it takes to wait for a response.
Does not support OOP-based objects
Less amenable to scalability
NoSQL (Not just SQL) or just non-relational databases
Databases of this type do not have a structured schema for writing data, and most databases contain json records. The database data is divided into several types, I will specify only two of them.
Key-Value
Such databases do not support normal queries between different record values. Here everything works as follows: you request a key and get its value, an example of such a database can be considered Redis.
Graph
In this database, data is stored in special lead the form of graphs and they are very flexible with a clear structure. Databases of this type are often used in social networks. An example of this database can be considered OrientDB or InfiniteGraph
Positive
Easy to achieve scalability
Speed of work
Minuses
They are updated for a long time because the information can be stored on different servers
Does not match ACID
Conclusion
It is impossible to say exactly what is best to use in one case or another, it all depends on the needs of each user. In order to find out exactly which one is more suitable for your needs, it is better to listen to the opinions of other users and their experience. Also, you can always answer a few questions that will help you understand which database is best to use.