What is a Deductive Database?

Question

I am reading some papers on databases and stumbled upon deductive databases. It seems that information on them is somewhat limited. The Wikipedia article states A deductive database is a database system that can make deductions (i.e. conclude additional facts) based on rules and facts stored in the (deductive) database., but that is somewhat of a vague explanation. How are rules stored in databases? I read about Datalog as a query language for such databases, but I also read this article. https://www3.cs.stonybrook.edu/~warren/xsbbook/node11.html#:~:text=Prolog%20is%20an%20elegant%20language,a%20powerful%20subset%20of%20SQL. Now the question becomes how is a deductive database different from a system constructed by a regular SQL database and analyzed by an application written in a logical programming language such as Prolog. I apologize if my questions are plain stupid, but it's hard to grasp on their real intention. Are there any real uses nowadays for such databases? All the papers I read on them are from 1990 and there don't seem to be any new advancements.