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?
Une table RésultatsExamens enregistre une note par candidat et par épreuve. Ni IDCandidat ni IDÉpreuve ne sont uniques à eux seuls. Quelle clé primaire convient ?
Answers
AThe Score column, since every candidate's score is differentLa colonne Note, puisque la note de chaque candidat est différente
BCandidateID on its own, allowing repeated valuesIDCandidat seul, en autorisant les valeurs répétées
CThe combination of CandidateID and PaperID (a composite key)La combinaison d'IDCandidat et d'IDÉpreuve (une clé composite)
DNo key is needed for this kind of tableAucune clé n'est nécessaire pour ce type de table
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