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
Link: Slides for Lecture 4
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