ER Diagram (Entity-Relationship)
About
An ER Diagram represents data models and relationships between entities in a database. It is widely used in database design and schema planning.
Refer to the official documentation for more details - https://plantuml.com/er-diagram
Key Elements
Entities
Represented as rectangles, denoting real-world objects (e.g.,
Customer
,Order
).
Attributes
Represented as ellipses connected to entities.
Primary Key (PK) – Unique identifier (underlined).
Foreign Key (FK) – Connects to another entity.
Relationships
Represented as diamonds between entities (e.g.,
Places Order
).1:1, 1:M, M:N relationships specify cardinality.
Cardinality & Participation
(1,1), (0,N), (M,N) define relationship constraints.
1. Employee Management System
This represents database entities and relationships for an Employee Management System.
Entities (
entity Name { }
).Primary Keys (
* field : type
).Relationships (
}|..||
).
2. Order System
This represents tables and their foreign key constraints.
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