What books/courses would you recommend for learning database modeling?

Question

Database design

I ask you to share materials for studying database modeling for the web.
Interested in things like:

• Messaging between users;
  
• Ability to add a user to friends;
  
• Creating a balance for the user.
  

It would be just perfect if the training materials were with real examples of the above things.

Answer 1

Messaging between users;
Ability to add a user to friends;
Creating a balance for the user.
A of the above

database modeling

?
All that you described is the business logic described on the server, it is very difficult to interpret this through the database.
Here is an understanding of relationships in relational relationships - yes. Relationships - 1:1, 1:n, n:n
I liked this course

Answer 2

Messaging between users;
Ability to add a user to friends;
Creating a balance for the user.

all this does not apply at all to databases, nor to their modeling.
try to google on the topics listed without adding the phrase "databases" to the query