A table Employees(EmployeeID, Name, DistrictID, DistrictName) has EmployeeID as its key. DistrictName depends on DistrictID, not directly on EmployeeID. Which rule does this break, and what is the fix?
Une table Employés(IDEmployé, Nom, IDDistrict, NomDistrict) a IDEmployé pour clé. NomDistrict dépend d'IDDistrict, et non directement d'IDEmployé. Quelle règle cela enfreint-il, et quelle est la correction ?
Answers
A1NF; split Name into first and last name columnsLa 1FN ; séparer Nom en colonnes prénom et nom de famille
B2NF; add DistrictID to the primary keyLa 2FN ; ajouter IDDistrict à la clé primaire
CNo rule; storing DistrictName here is always bestAucune règle ; stocker NomDistrict ici est toujours préférable
D3NF (transitive dependency); move DistrictName to DistrictsLa 3FN (dépendance transitive) ; déplacer NomDistrict dans Districts
The answer and explanation are in the full bank.
This question is one of 2,831 in the paid banks. Each comes with the correct answer and the reasoning behind it, not just a mark.
Unlock for 5,000 RWFMIFOTRA exam practicealigned to Practice set: Database Management·3 marks·Hard
More Database questions
- What is the main role of a database management system (DBMS) such as PostgreSQL, MySQL or SQL Server?
- In a relational table called Applicants, what does a single row represent?
- Which two properties must every primary key value have?
- The Employees table has a DistrictID column that must always refer to an existing row in the Districts table. What enforces this rule?
- An ExamResults table records one score per candidate per paper. Neither CandidateID nor PaperID is unique on its own. What is a suitable primary key?
- A designer gives each applicant an auto-generated ApplicantID as the primary key, and stores the national ID number as a separate unique column. Why use this surrogate key?
- One district has many sectors, and each sector belongs to exactly one district. What type of relationship is this?
- Each trainee can attend many courses, and each course has many trainees. How is this relationship stored in a relational database?