Title slide
Slides : Recording

Today’s lecture reviewed the high-level conceptual language of ER diagrams and the more concrete structures of the relational model; followed by some recipes for translating from the first into the second. This isn’t always an exact match, and for any particular ER diagram we might go back to its original scenario description to decide how to best represent it as a relational model. Even so, this kind of step-by-step staging towards a fully formal representation is an effective route to capturing the subtleties of real-world systems.

The lecture covered in particular translating the following ER idioms into the relational model of linked tables.

  • Entities, relationships, and their attributes
  • Key constraints
  • Participation constraints
  • Weak entities
  • Entity hierarchies

You’ll see this material again in Tutorial 2, where you will get to apply the methods to specific examples.

Links: Slides for Lecture 4; Recording of Lecture 4

Do This
Title page of tutorial exercises

Download the exercises for Tutorial 1: Entity-Relationship Modelling. Read the instructions on the front page and work through the questions.

Where you find parts difficult, or have questions: stop and ask other students; post on Piazza, or ask at InfBASE.

Write out your solutions and working. Bring them to your tutorial meeting: you may need to show them to your tutor or exchange them with other students.

The sheets also have several more example problems and notes on solving them. You might also find the exercises from the reading homework helpful practice.

Link: Inf1-DA Tutorials

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Link: DICE ifile page

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Link: InfBASE home page

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Links: Informatics computing help; Remote working; Computing support form

Lecture 4: From ER Diagrams to Relational Models