Software Design

Library Data Modeling: Titles vs Physical Copies

UML Class Diagrams · made in Skemio

Class diagram showing BookTitle aggregated into BookCopy, which participates in a Loan association with Patron.
Class diagram showing BookTitle aggregated into BookCopy, which participates in a Loan association with Patron.
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What it shows

  • A Book Title holds metadata (ISBN, author, description) shared across all copies.
  • A Physical Copy tracks bar code, condition, shelf rack, and loan state.
  • Separating title from copy avoids duplicating metadata across physical inventory.

The takeaway

Separate the abstract intellectual work from the inventory asset holding real-world state.

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