Describe: 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)
Draw a ER diagram model for a small college with the classes/entities: Student, Instructor, Course, Project
You can use an online tool such as: https://app.diagrams.net/
The rules are:
All students must be enrolled in at least one course or one project
An instructor must teach at least one course og supervise at least one project
A student cannot be working on more than one project (they're too time consuming)
An instructor can teach any number of courses and supervise any number of projects
A project or course must have an instructor
A course must have at least 1 student (or it is cancelled)
Last updated 6 months ago
