03 ER and Relational Data Models
Lesson: https://webeep.polimi.it/mod/resource/view.php?id=30596 Exercises: https://webeep.polimi.it/mod/resource/view.php?id=32921
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01 ER
Foundations An entity–relationship model (or ER model) describes interrelated things of interest in a specific domain of knowledge. A basic ER model is composed of entity types (which classify the…
02 Relational Model
Keys Superkey : a set of attributes K is a superkey for a relation r if r does not contain two distinct tuples t1 and t2 with t1[K]=t2 [K]; Key : K is a key for r if K is a minimal superkey (that is,…
03 ER Exercises
Exercise 1 Design an ER Model for a car rental system that manages the customers, the cars and their related elements. If a customer wants to rent a car, they should provide their personal ID card…