Notes on Database Management System

Data: Raw facts, figures, and information used for various purposes, organized into three main types:
Structured Data: Organized and formatted (e.g., spreadsheets, relational databases).
Semi-Structured Data: Some organization but not rigidly formatted (e.g., XML files).
Unstructured Data: Lacks specific format (e.g., text documents, images).

Database: Collection of data for rapid search and retrieval.
Represents aspects of the real world, logically structured for specific purposes.
Database Management System (DBMS): Software that allows users to create, maintain, and manipulate databases.
Functions:
- Defining: Specify data types and structures.
- Constructing: Store data on a storage medium.
- Manipulating: Querying and updating data, generating reports.

Data Redundancy Control: Minimizes duplicate data, saving space and ensuring consistency.
Data Integrity: Rules and constraints maintain data accuracy over time.
Data Security: Features like user authentication and encryption protect data access.
Data Consistency: Centralized data ensures updates are consistent system-wide.
Data Sharing: Allows multiple users to access data simultaneously.
Backup and Recovery: Automated systems protect against data loss.
Data Independence: Changes in the schema do not affect application programs.
Query Language Support: Users can interact with data using SQL without extensive programming.
Scalability: Handles growing amounts of data efficiently.
Concurrent Access: Multiple users can access data safely through mechanisms like locking.
Improved Performance: Through indexing and query optimization.
Complex Data Structures: Supports multimedia and complex data types
Reduced Development Time: Provides tools for faster application development.
Wide Applicability: Useful in various industries (banking, healthcare, etc.).

ACID Properties: Atomicity, Consistency, Isolation, Durability.
Multiple User Access: Supports concurrent user connections.
Backup and Recovery Systems: Protect data integrity and recover from failures.
Query Language Support: Tools provided for easy data manipulation (e.g., SQL).

Hardware: Physical equipment like servers and storage devices.
Software: DBMS software for managing data.
Data: The actual information being managed.
Procedures: Guidelines for data management.
Database Design: Structure represented by tables and relationships.
Database Models: Frameworks for organizing and representing data (e.g., relational model).
Users: Different types based on interaction (end-users, administrators, developers).
Security and Access Control: Protocols to limit data access.
Query Processor: Optimizes user queries.
Transaction Management: Ensures data integrity during operations.
Storage Management: Handles data storage logistics.
Backup and Recovery Procedures: Methods for data restoration.
Concurrency Control: Manages simultaneous user access.

1-Tier Architecture: Direct access to the database; minimal user interface.
2-Tier Architecture: Client-server model; clients interact directly with servers using APIs.
3-Tier Architecture: Has an application server between client and database, isolating users.

Logical Data Independence: Changing the conceptual schema does not affect the external schema.
Physical Data Independence: Changes in internal schema do not affect the conceptual schema.

Data Definition Language (DDL): Commands for defining database structures.
Data Manipulation Language (DML): Operations for data retrieval and updates.
Data Control Language (DCL): Controls permissions using statements like GRANT and REVOKE.

Increased Costs: Maintenance and training can be expensive.
Management Complexity: Need for skilled personnel and technology integration.
Maintenance and Updates: Frequent updates required for security and efficiency.
Overhead Costs: General DBMS features may not be needed for simple applications.