Cardinality & Diagrams
Cardinality, ER & EER Diagrams
Crows foot notation
Crows foot notation
https://vertabelo.com/blog/crow-s-foot-notation/
Exercise 1 study groups: Identify the primary key
What is a primary key? What are the characteristics
What could be the primary key from the following database schemas? If none answer that
person(navn, fødselsdato, addresse, bruger_briller, cpr_nummer)
bil(farve,stelnummer,nummerplade, mærke, model)
sang(kunstner, album, længde, danceability, genre)
film(titel, hovedrolle, genre, årstal, instruktør)
hvem_står_i_kø(navn, alder, hårfarve, nummer_i_kø)
Exercise 2:
Identify the entities of the case defined at the bottom
Exercise 3
Create an ER diagram in Chen or Crows foot notation —including entity types, relationships, cardinality and attributes —for managing a large movie database. It is up to you if you use existing tools for data modeling or draw this by hand. (I suggest discussing by hand and finalizing by software such as: https://www.lucidchart.com/pages/)
There are multiple correct ways of modeling this discourse, however the diagram should capture the following information from the stakeholders:
Case: study groups
In this case - we are in the process of building an alternative to IMDB
We will not be writing the database ourselves, but need to communicate the design to a developer team
For this we need to take business requirements and create a comprehensive piece of documentation
A movie has a unique ID, an original title, an English title (translation), a release date, a runtime in minutes, and an optional homepage. Each movie had a certain budget (production cost) and revenue (income yielded so far). Based on the budget, movies are classified as low-, medium- and high-budget productions.
A movie can be produced in arbitrarily many countries, each being described by an ISO 3166-1 alpha-2 country code, and name. Movies are further described by a list of genres, the language of the original title, and a list of spoken languages. Every language has an ISO 639-1 code, and an endonym (i.e., internal) name.
The cast of a movie is composed of one or multiple actors, each playing one or multiple roles (characters) in the movie. A single actor might belong to the cast of one or many movies, has a unique ID, a non-unique name, a gender (1 female, 2 male, 3 non-binary), and lives in exactly one country.
Every movie might receive an unlimited number of user ratings. A single rating of a movie is characterized by a score (scale 0.5-5), a date, and an anonymous user ID. A single rating refers to exactly one movie.
Modified from: https://mboehm7.github.io/teaching/ws2021_dbs/01_ExerciseModeling.pdf
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