Data Modeling Basics

Data Modeling

• Data modeling is the first step in database design, connecting real-world objects to a computer database.
• A data model is a simplified representation, often graphical, of intricate real-world data structures.
• Data modeling involves analyzing organizational and user data requirements.
• Data requirements can be identified through policies, meetings, procedures, system specifications and more.
• Data models help to identify what data is important and what data should be maintained.

Importance of Data Modeling

• Data models serve as blueprints for database design, providing official documentation.
• Data models can be understood by employees without database knowledge, making them effective communication tools.
• They facilitate better interaction between managers, designers, and end users.
• Data models are independent of a specific Database Management System (DBMS), meaning they can be used with different DBMS types like Network or Object-oriented DB.

Entity Relationship Diagram (ERD)

• An ERD is a data modeling technique used to visually represent the conceptual data model of an information system.
• ERDs illustrate the logical structure of databases.
• ERD development is often assisted by Computer-Aided Software Engineering (CASE) tools like Powerdesigner by SAP.
• The primary task in ERD creation is to identify entities, attributes, and their relationships.

Entities, Attributes, and Relationships

• Entities represent objects, people, places, events, or concepts about which data is stored.
• Entity instances are individual occurrences of an entity.
• Attributes are data objects that identify or describe entities, essentially properties of an entity.
• Relationships are connections between entities, often indicated by verbs connecting two or more entities.
• Cardinality refers to the number of instances of one entity that can be associated with a specific instance of another entity.
• Relationships can be classified as one-to-one, one-to-many, or many-to-many.