Pertemuan 2 : Pengantar Basis Data - Entity Relationship Diagram (E-R Diagram)

Introduction

This tutorial provides an introduction to Entity Relationship Diagrams (E-R Diagrams), which are essential for database design. Understanding E-R Diagrams helps visualize data relationships and structures, making it easier to create efficient databases. This guide will walk you through the fundamental concepts and steps to create an E-R Diagram.

Step 1: Understand the Basics of E-R Diagrams

• Definition: An E-R Diagram is a graphical representation of entities and their relationships in a database.
• Components:
  • Entities: Objects or things in the database (e.g., Student, Course).
  • Attributes: Properties of entities (e.g., Student Name, Course Code).
  • Relationships: Connections between entities (e.g., Enrollment between Student and Course).

Step 2: Identify Entities

• Start by listing the key entities relevant to your system.
• Example Entities:
  • Student
  • Course
  • Instructor
• Ensure each entity has a clear purpose in the context of your database.

Step 3: Define Attributes

• For each entity, identify its attributes.
• Example for Entity "Student":
  • Student ID
  • Name
  • Date of Birth
• Attributes should provide necessary details about the entity.

Step 4: Establish Relationships

• Determine how entities interact with each other.
• Common relationship types:
  • One-to-One (1:1): Each entity in the relationship will have exactly one counterpart.
  • One-to-Many (1:N): One entity can have multiple counterparts.
  • Many-to-Many (M:N): Entities can have multiple counterparts on both sides.
• Example Relationship:
  • A Student can enroll in multiple Courses (1:N).

Step 5: Create the E-R Diagram

• Use diagramming tools (like Lucidchart, Draw.io, or even pen and paper) to visualize your E-R Diagram.
• Follow these layout tips:
  • Place entities as rectangles.
  • Use ovals for attributes connected to their respective entities.
  • Draw diamonds for relationships, connecting relevant entities.
• Ensure clarity and readability by avoiding clutter.

Step 6: Review and Refine

• Check your E-R Diagram for accuracy:
  • Ensure all entities and relationships are represented.
  • Validate that the attributes correctly describe each entity.
  • Confirm that the relationships reflect real-world interactions.
• Gather feedback from peers or instructors for further refinement.

Conclusion

Creating an E-R Diagram is a foundational skill in database design. By following these steps, you can effectively represent the structure of your database. Remember to continually refine your diagram as your project evolves. For next steps, consider learning about normalization to further improve your database design.