Translating from ER to Relationship Schema

Translating from ER to Relationship Schema

Adapted from Juliana Freire

The easy partEntity relation with attributes

underlined field is keyRelationship -> relation?

special situations– Multi-valued and composite attributes– Weak entity sets– ISA relationships– Relations that result from an entity set and 1tomanyrelationship

Translating Many-to-Many

One to Many

One to Many answer

One – to- Many

One to Many with total participation

Why not a new relation?

Mapping many to many attribute

Throw the attributes onto the relationship table

1-to-many relationship with an attribute?

Add it to the 1 side

Translating Weak Entity Sets

Translating ISA relationship – as a tier

Translating ISA – one with all

Which one?

Participation Constraints

Splitting tables is always an option

Sample ERD

Equivalent Relational Schema

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Translation steps