Consider the following ER diagram, where the owns relationship is 1-to-1 as displayed, which is the best practice for mapping of the owns into a relation?
Understand the Problem
The question is asking about best practices for mapping a one-to-one relationship from an Entity-Relationship (ER) diagram into a relational database. Specifically, it focuses on the relationship between a PERSON and a MOBILE entity as depicted in the ER diagram.
Answer
Add MOBILE's 'mnumber' as a foreign key in PERSON.
The best practice is to incorporate the primary key of one entity as a foreign key in the other entity. In this case, adding Mobile's 'mnumber' as a foreign key in the PERSON table is one common approach.
Answer for screen readers
The best practice is to incorporate the primary key of one entity as a foreign key in the other entity. In this case, adding Mobile's 'mnumber' as a foreign key in the PERSON table is one common approach.
More Information
For 1-to-1 relationships, you typically add a foreign key from one entity's primary key into the other entity without creating a separate relationship table. This is efficient and simplifies your schema.
Tips
Common mistake: Creating a separate table for 1-to-1 relationships, which is unnecessary.
Sources
- Mapping from ER Model to Relational Model - GeeksforGeeks - geeksforgeeks.org
- The Basics of One-to-One Relationships in ERD - Gleek.io - gleek.io
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