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tarlyo
tarlyo

Reputation: 1

How do weak attributes convert from ER diagram to relational schema?

I am creating an ER diagram and relational schema for a school project. In my ER diagram, I have shown attributes like "street name" and "city" as weak attributes of another attribute "address." How would I convert this to a relational schema? Do weak attributes even appear in my relational schema?

Part of my ER Diagram

Upvotes: 0

Views: 1598

Answers (1)

reaanb
reaanb

Reputation: 10066

I prefer to call Billing Address a composite attribute, and City a component attribute.

The term "weak" is used in ER diagrams to describe entity sets that include another entity set's key as part of its own. For example, if an Invoice is identified by an Invoice_ID, and contains LineItems that are identified by Invoice_ID, Line_Number, that would make LineItem a weak entity set, and Line_Number would be its weak key.

When converting composite/component attributes to a relational schema, the simplest approach is to use only the component attributes. This means the composite attributes are nothing more than a visual aid.

Upvotes: 1

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