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Database

Chapter 2 The ER-Data Model and Mapping to Relational Schema

Show Source |    | About   «  2.3. ERD Mapping To Relational Data Model   ::   Contents   ::   2.5. ERD Relationship Types  »

2.4. ERD Different Notations

Notation means: collection of symbols used for specific data representations purposes in database design modelling.

What are the components of Chen notation?

What are the components of Crow’s Foot notation?

What is Min-Max notation:

Note: From here all the following visualizations not only represented by ERD models but also these models were mapped to the corresponding relational schema for best illustration.

These below visualization show you how to represent basic ERD elements (Entities, attributes & relations) in both (Chen & Crow’s foot) notations:

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Chen vs Crow’s foot notaion For Composite Attribute:

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Chen vs Crow’s foot notaion For Multivalued Attribute:

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Hint: In the relational schema the multivalued attribute of the ER model converted to a separate table with a relation with its original table. The primary key of the new multivalued attribute table is composed of both the value of the attribute itself & the FK that references the original table.

_images/MultivaluesAttEX.png

Chen vs Crow’s foot notaion For Derived Attribute:

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   «  2.3. ERD Mapping To Relational Data Model   ::   Contents   ::   2.5. ERD Relationship Types  »

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