ER Model Fundamentals: Entities, Attributes, and Relationships
The ER model defines the conceptual view of a database. It works around real-world entities and the associations among them. At the view level, the ER model is considered a good option for designing databases.
Entity Concepts in the ER Model
An entity can be a real-world object, either animate or inanimate, that can be easily identifiable. For example, in a school database, students, teachers, classes, and courses offered can be considered entities. All these entities have attributes or properties
Read MoreSystem Analysis, SDLC, and Data Modeling Essentials
System Analysis and Design (SA&D) Importance
Systems analysis and design (SA&D) provides the tools and techniques necessary for developers to:
- Understand the business need.
- Capture the vision and define a solution.
- Communicate the vision and the solution effectively.
- Build the solution and direct others in its construction.
- Confirm that the solution meets the need.
- Launch the solution application.
The Role of SA&D: Customer Needs vs. Developer Tasks
Users/Customers often express needs like:
- “I
Systems Analysis: Requirements, Decomposition, and Modeling
Systems Analysis: Decomposition and Requirements
Systems analysis involves decomposing a system into components for individual study and understanding their interactions. The goal is to produce a requirements document that describes what the future system should do, focusing on what rather than how. Requirements analysis is the process of thoroughly studying these requirements.
Prerequisites: Defining Requirements
A requirement is defined as a condition or capability needed by a user to solve a problem
Read MoreEntity Relationship Model: Attributes, Entities, and Relationships
ER Model: Attributes, Entities, and Relationships
Attribute Definitions
- Composite Attribute: An attribute composed of multiple components. Example: Full Name (First Name, Last Name).
- Derived Attribute: An attribute calculated from other attributes. Example: Age (from Date of Birth).
- Single-Valued Attribute: An attribute with only one value. Example: Social Security Number.
- Multivalued Attribute: An attribute with multiple values. Example: Phone Numbers.
- Simple Attribute: An attribute that cannot