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Entity Relationship Diagram Guide

Yapay zekadan makale özeti

What is ERD: ERD visualizes major entities and their relationships in database design
Entities represent business objects like people, products, or events
ERD uses symbols like rectangles and connectors to depict entities and relationships
When to Use ERD: Helps visualize database design before changes can affect production
Assists in database debugging by showing entire schema
Supports database creation and patching through automated tools
Aids in requirements gathering for information systems
ERD Levels: Conceptual model shows business objects and relationships
Logical model defines columns and operational entities
Physical model represents actual database structure
Physical model must match database system conventions
Key Components: Entities are shown as rectangles with names and attributes
Primary keys uniquely identify database records
Foreign keys reference primary keys in other entities
Cardinality defines relationships between entities
Relationship Types: One-to-one relationship shows one entity linked to one other
One-to-many relationship links one entity to many others
Many-to-many relationship links multiple entities to many others
Implementation: ERD should be drawn with clear purpose and scope
Relationships between entities must have proper cardinality
Normalization can reduce data redundancy
Can be used with DFD and BPMN diagrams for system analysis