Everything is connected with everything else one way or another. You don't have to be a fan of conspiracy theories, to be a believer in some specific religion, to be exceptionally intelligent or have some "super" gene to be able to become aware of it, to see it, to comprehend it, to live it.
If you've watched Discovery Chanel or Animal Planet about the cycles in the nature - you'll have seen that - the number of any living being inside the food chain could cause variations in the other layer. If there are too little plants, the grass-eating animals will become less (or will migrate), and that influences the hunting animals. If there are too many predatory animals, this will diminish the number of grass eating animals and that will influence positively on the grass and the plants.
Connections and a cause and effect relations between events, habits, activities can be found also in the human society at micro level - in small scale, even in a single human life, and also at a macro level - where are we going as a species, as a civilization - in terms of numbers, technology, relationship between each other. And actually, if one is to study history, could see numerous repetitions.
Money could be used as a indicator for connectivity in the human society. Blockchain raised 10 years ago and right now there are A LOT of crypto-currencies and their price in terms of fiat currency is in more than 99% linked together. When one crypto price goes up, others follow, when others go down, others sooner or later go down too. 2008 was a year of crisis that showed how connected are the banks around the world. The World is so connected so the politics influence the smallest economics - in the smallest countries around that are located near the storm of influence - and this is about life-long life hood, productions that have raised families, villages and even medium to big size cities.
In the technology sector - Oracle placed a bet on relational databases and technologies around 20 - 25 years ago and won. Today, thanks to the success of the relational databases - the relations between all kinds of data is embedded to the lowest level all around the Internet and can be seen and perceived in all the big sites - Facebook - connecting friends, people, organizations, pictures, events, interests, comments, etc, Linkedin - linking people and the technological skills they have and with each other and with human resources, e-commerce sites - linking categories, products, user reviews, prices, blogging platforms (used for more than just blogging) - linking topics, articles, posts, pages, writers - powering more than one - third of the Internet and so on.
I myself have a small contribution (probably I am not the only one in doing this) in implementing some custom relations. One of my sites/products : kakvoiadesh.com is focused around the food products and items and the good ingredients, the bad ingredients, the organs of human body, the allergies and the diseases that the food items are beneficial or harmful to and so on.
What I also found that, at least for now, not everything can be modeled to computer models and relations (not that I know a lot of mathematics, but still). That's why I wrote a book - My Path to the Health. There are things that the human mind cannot comprehend like the power of the human mind and intention and internal motivation and strength (psychology).
I have written and recorded myself before (audio and video) about the different ways to handle data:
And a product that I am focusing a lot now is https://tomavelev.com/GeneratorApp/ It generates a SQL, a database layer in some language (PHP, Java, Kotlin), some more layers here and there, and a User Interface with the basic operations over your data definitions.
The last few years I focused a little bit more on Android.
I am fully aware that this OS may fade out of existence, but the other part - the core code about processing data will most likely still be usable - no matter what the interface to the user will arise - Voice Services like Assistant or Alexa, or Messanger bots - Like Facebook Messanger, Viber or Telegram or something totally new. They all will need some layer for processing the data in a structured way and currently the RDBS are one of the finest way to structure your information.
Single Responsibility Principle (or SRP) is one of the most important concepts in software development. The main idea of this concept is: all pieces of software must have only a single responsibility.