sudhanshutiwari264 / Chat-Application-Database

The Chat Application Model Database is designed to provide a robust and structured data storage solution for a chat application. It serves as the backbone for managing user accounts, friend relationships, and chat messaging features within the application. This comprehensive documentation covers the database .

Chat Application Model Database Documentation

Database Overview

The Chat Application Model Database is designed to provide a robust and structured data storage solution for a chat application. It serves as the backbone for managing user accounts, friend relationships, and chat messaging features within the application. This comprehensive documentation covers the database schema, tables, relationships, sample queries with outputs, and details about the implemented triggers.

ER-Diagram

Database Schema

The database schema consists of four primary tables: admin, users, friends, and messages. Each table serves a distinct purpose in supporting various aspects of the chat application.

Users Table

• Columns:
  • ID (INT, Primary Key): Unique identifier for each user.
  • Username (VARCHAR): User's username.
  • Email (VARCHAR): User's email address.
  • Status (VARCHAR): User's status, can be 'Active' or 'Inactive'.
  • AuthenticationTime (DATETIME): Timestamp of the user's last authentication.

Friends Table

• Columns:
  • ID (INT, Foreign Key): User ID.
  • FriendID (INT, Foreign Key): Friend's ID.

Messages Table

• Columns:
  • ID (INT, Primary Key): Unique identifier for each message.
  • FROMUID (INT, Foreign Key): Sender's ID.
  • ToUID (INT, Foreign Key): Receiver's ID.
  • MessageText (TEXT): The content of the message.
  • SentDt (DATETIME): Timestamp when the message was sent.
  • ReadStatus (VARCHAR): Message read status, can be 'Read' or 'Unread'.

Triggers

1. updateAuthenticationTime Trigger:

   • Function: Updates the AuthenticationTime of the sender when a new message is sent.

2. updateUserKey Trigger:

   • Function: Updates the UserKey based on the user's Status before each update.

3. updateUserKeyOnStatusChange Trigger:

   • Function: Updates UserKey when there is a change in the user's Status.

4. updateAuthTimeOnFriendAdd Trigger:

   • Function: Updates AuthenticationTime for users involved in a new friendship.

5. updateUserStatusOnNoFriends Trigger:

   • Function: Updates user status to 'Inactive' if they have no friends.

6. updateUserStatusOnUnreadMessages Trigger:

   • Function: Updates user status to 'Active' if they receive a new unread message.

7. deleteOldMessages Trigger:

   • Function: Deletes messages older than 6 months after a new message is inserted.

Stored Procedures

1. SendMessage Stored Procedure:

   • Function: Inserts a new message into the messages table.

   CALL SendMessage(1, 2, 'Hello, Sheetal!');

2. markAllMessagesAsRead Stored Procedure:

   • Function: Marks all messages as read for a specific user.

   CALL markAllMessagesAsRead(1);

3. deleteUserAndMessages Stored Procedure:

   • Function: Deletes a user and their associated messages.

   CALL deleteUserAndMessages(2);

4. getFriendList Stored Procedure:

   • Function: Retrieves a list of friends for a user.

   CALL getFriendList(1);

5. getLatestMessage Stored Procedure:

   • Function: Retrieves the latest message for a specific user.

   CALL getLatestMessage(1);

Queries

1. Retrieve all users and their friendships:

   SELECT u.ID AS UserID, u.Username, u.Email, f.FriendID, fu.Username AS FriendUsername, fu.Email AS FriendEmail
   FROM users u
   JOIN friends f ON u.ID = f.ID
   JOIN users fu ON f.FriendID = fu.ID;

   Example Output:

   UserID	Username	Email	FriendID	FriendUsername	FriendEmail
   1	Sudhanshu	[e-mail]	2	Sheetal	[e-mail]
   1	Sudhanshu	[e-mail]	3	Arun	[e-mail]
   2	Sheetal	[e-mail]	1	Sudhanshu	[e-mail]
   3	Arun	[e-mail]	1	Sudhanshu	[e-mail]

2. Fetch messages sent by a specific user with sender and receiver details:

   SELECT m.ID AS MessageID, m.FROMUID AS SenderID, u1.Username AS SenderUsername,
          m.ToUID AS ReceiverID, u2.Username AS ReceiverUsername, m.SentDt AS SentDateTime, m.MessageText
   FROM messages m
   JOIN users u1 ON m.FROMUID = u1.ID
   JOIN users u2 ON m.ToUID = u2.ID
   WHERE m.FROMUID = 1;

   Example Output:

   MessageID	SenderID	SenderUsername	ReceiverID	ReceiverUsername	SentDateTime	MessageText
   1	1	Sudhanshu	2	Sheetal	2023-01-01 12:00	Hello, Sheetal!
   2	1	Sudhanshu	3	Arun	2023-01-02 14:30	Hi, Sudhanshu!

3. Obtain all messages exchanged between friends:

   SELECT m.ID AS MessageID, m.FROMUID, m.ToUID, m
   
    .SentDt, m.MessageText
   FROM messages m
   JOIN friends f ON (m.FROMUID = f.ID AND m.ToUID = f.FriendID) OR (m.FROMUID = f.FriendID AND m.ToUID = f.ID);

   Example Output:

   MessageID	SenderID	ReceiverID	SentDateTime	MessageText
   1	1	2	2023-01-01 12:00	Hello, Sheetal!
   2	2	1	2023-01-02 14:30	Hi, Sudhanshu!

4. Identify unread messages for a specific user:

   SELECT m.ID AS MessageID, m.FROMUID, u.Username AS SenderUsername, m.ToUID, m.SentDt AS SentDateTime, m.MessageText
   FROM messages m
   JOIN users u ON m.FROMUID = u.ID
   WHERE m.ToUID = 1 AND m.ReadStatus = 'Unread';

   Example Output:

   MessageID	SenderID	SenderUsername	ReceiverID	SentDateTime	MessageText
   3	3	Arun	1	2023-01-03 10:45	Unread message

5. List users with a specific status:

   SELECT ID AS UserID, Username, Email, Status
   FROM users
   WHERE Status = 'Active';

   Example Output:

   UserID	Username	Email	Status
   1	Sudhanshu	[e-mail]	Active
   2	Sheetal	[e-mail]	Active

6. Retrieve messages sent by users with a specific status:

   SELECT m.ID AS MessageID, m.FROMUID, u.Username AS SenderUsername, m.ToUID, m.SentDt AS SentDateTime, m.MessageText
   FROM messages
   JOIN users u ON m.FROMUID = u.ID
   WHERE u.Status = 'Active';

   Example Output:

   MessageID	SenderID	SenderUsername	ReceiverID	SentDateTime	MessageText
   1	1	Sudhanshu	2	2023-01-01 12:00	Hello, Sheetal!
   2	2	Sheetal	1	2023-01-02 14:30	Hi, Sudhanshu!
   3	3	Arun	1	2023-01-03 10:45	Unread message

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🌟 Thank you for exploring the Chat Application Model Database! 🚀

We believe in the magic of connecting people through technology. May your coding journey be as smooth as a well-optimized SQL query and your friendships as resilient as a robust database schema.

Feel free to reach out for any queries, collaborations, or just to share your success stories. Happy coding, and may your code always compile without errors!

Keep sparking creativity, keep building connections! 🌐✨

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