Scenario: There are 3 entities - user, chat, message - User has a name and registration date - Chat has a name and creation date - Message has text, author, and creation date - A user can be part of multiple chats simultaneously - A message must belong to a chat, and cannot belong to more than one chat at the same time - Describe the domain model in the form of tables

To describe the domain with users, chats, and messages, the following tables and relationships can be used:

1. users — users table

• id (PK)
• name (varchar)
• registration_date (datetime)

2. chats — chats table

• id (PK)
• title (varchar)
• creation_date (datetime)

3. messages — messages table

• id (PK)
• chat_id (FK -> chats.id)
• author_id (FK -> users.id)
• text (text)
• creation_date (datetime)

4. user_chats — many-to-many relationship table between users and chats

• user_id (FK -> users.id)
• chat_id (FK -> chats.id)
• PRIMARY KEY (user_id, chat_id)

Explanation:

• A user can be part of multiple chats — the many-to-many relationship is implemented through the user_chats table.
• A message belongs to one chat and one author — the messages table has foreign keys to chat_id and author_id.

This modeling allows efficient storage and querying of data about users, chats, and messages.