E-R Diagram: Best Design
An entity–relationship diagram using Chen's notation
Symbols:
Derived attributes are depicted by dashed ellipse.
Cardinality Relationship:
Relationship with foreign key
Generalization:Generalization is a bottom-up approach in which two lower level entities combine to form a higher level entity. In generalization, the higher level entity can also combine with other lower level entity to make further higher level entity
Specialization:Specialization is opposite to Generalization. It is a top-down
approach in which one higher level entity can be broken down into two
lower level entity. In specialization, some higher level entities may
not have lower-level entity sets at all.
Aggregration: Aggregration is a process when relation between two entity is treated as a single entity. Here the relation between Center and Course, is acting as an Entity in relation with Visitor.
An entity–relationship diagram using Chen's notation
Cardinality Relationship:
Relationship with foreign key
Participation Constraints
- Total Participation − Each entity is involved in the relationship. Total participation is represented by double lines.
- Partial participation − Not all entities are involved in the relationship. Partial participation is represented by single lines.
Generalization:Generalization is a bottom-up approach in which two lower level entities combine to form a higher level entity. In generalization, the higher level entity can also combine with other lower level entity to make further higher level entity
Aggregration: Aggregration is a process when relation between two entity is treated as a single entity. Here the relation between Center and Course, is acting as an Entity in relation with Visitor.
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