Introduction to Databases

• A database constitutes an organized compilation of data, potentially encompassing words, videos, images, numbers, and more, stored electronically.

Key Features of Databases

• Organized data storage uses structured formats like tables, documents, or key-value pairs.
• Data retrieval is quick due to efficient access via advanced search functionalities and query capabilities.
• Security and scalability are provided, databases have strong security measures and the ability to expand with increasing data input.

Importance of Databases

• Databases enable efficient scaling to manage substantial volumes of data.
• Data integrity is maintained through built-in rules and conditions, ensuring data consistency and accuracy, even with extensive database growth.
• Data security features include user authentication, access control, and strict compliance with privacy regulations to protect sensitive data.
• Data analytics are supported by modern databases through tools that identify trends and patterns used by organizations for data-driven decision-making.

Components of a Database

• Essential components include data itself, schema (blueprint), DBMS (software layer), queries (commands), and users.

Database Management System (DBMS)

• A DBMS is a specialized software that allows users to manipulate data through storing, retrieving, editing, and deleting.
• DBMS tasks involve administration, storage, and concurrency control, allowing multiple users to access and modify data simultaneously.
• DBMS provides a centralized view so multiple users can access data from multiple locations in a controlled manner.
• Data manipulation is a key function.
• Data independence features both physical and logical independence, protecting users from concerns about data storage details or physical structure.
• Backups and recovery mechanisms are present.

DBMS Architecture

• Selecting the correct architecture impacts data management and system performance.

1-Tier Architecture

• The database is directly available to the user, commonly in personal or standalone applications like Excel.
• A 1-Tier Architecture do not require external server or network connections.
• Advantages include simplicity, cost-effectiveness, and ease of implementation.

2-Tier Architecture

• A client end communicates directly with the database on the server side
• The server manages query processes and transaction management.
• Advantages include easy access from client to server, scalability via hardware upgrades or increased client size, low cost, simplicity, and ease of implementation.

3-Tier Architecture

• Clients interact with an application server, which then sends data to the database for query processing and transaction management.
• This architecture is used in large web applications like E-commerce stores.
• Enhanced scalability (individual connections can still happen without being made in between the client and the server)
• Data integrity is improved because data corruption can be avoided with a middle layer.
• Security is enhanced as the model prevents direct interaction between the client and the server.
• Complex systems arise becuase more communication points exist.
• This can be Difficult to interact (Due to the presence of middle Layers).

Conceptual Data Model

• Conceptual Data Models offer an organization-wide view of business concepts.
• Designed for a business audience, focusing on real-world data representation.
• Conceptual Data Models are independent of hardware and software specifications such as (e.g., DBMS, storage, location)
• Domain Models, helps create a common vocabulary for stakeholders, defining basic concepts and scope

Representational Data Model

• Representational Data Model is used to represent the logical part of the database
• Focuses design of the database for the user
• An example is a Relational Model

Relational Model

• Relational Model is a technique in which the data is structured using relations. Commonly known as Tables.

Characteristics of Representational Data Model

• Defines the logical structure of a database.
• Represents data and relationships using tables.
• Forms the basis for the Physical Data Model.

Physical Data Model

• Details how a database is practically implemented using a specific DBMS.
• Focuses on physical storage, including files, records, and structures on secondary storage devices like disks and tapes.
• SQL is used to implement Relational Algebra.
• Created by DBAs and developers for the actual implementation of the database.