A foreign key is which of the following?
Answer: C
Correct answer: An attribute that serves as the primary key of another relation
A foreign key is how relations are joined: it holds the value of some other relation’s primary key, and referential integrity requires that value either to exist there or to be null. It may be part of its own relation’s primary key too, as in an associative relation.
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If no multivalued attributes exist in a relation, then the relation is in what normal form?
Answer: A
Correct answer: First normal form
First normal form is defined by every attribute being single-valued, so removing the multivalued attributes achieves it and nothing more. Partial and transitive dependencies may still be present, and removing those is what the higher forms are for.
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A relation is a two-dimensional table.
Answer: A
Correct answer: True
A relation is a two-dimensional table with the further restrictions that each cell holds a single value, all entries in a column are of one kind, no two rows are identical, and neither row nor column order carries meaning. A table meeting all of them is a relation; one that does not is merely a table.
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Relations are:
Answer: A
Correct answer: two-dimensional tables.
A relation has exactly two dimensions: rows, which are the tuples, and columns, which are the attributes. Everything else - hierarchies, time series, multidimensional analysis - must be expressed within that structure, which is both the model’s limitation and the source of its simplicity.
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If a relation is in third normal form, it does not need to be in second normal form.
Answer: B
Correct answer: False
The normal forms are cumulative: third normal form requires second, which requires first. A relation in third normal form is therefore already in second by definition, and the statement inverts that relationship entirely.
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In a 1:M relationship, the primary key on the one side migrates to the many side to become the foreign key on the many side.
Answer: A
Correct answer: True
A one-to-many relationship is represented by placing the primary key of the one side into the many side as a foreign key. It cannot go the other way: the one side would need to hold many values, which first normal form forbids. This is the commonest mapping rule of all.
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A synonym is two or more attributes that have different names but the same meaning.
Answer: A
Correct answer: True
Synonyms arise when two parts of an organisation give the same thing different names - client and customer, part number and item code. Finding them is part of integrating a model, since leaving them unresolved produces two attributes and eventually two sets of data for one fact.
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A primary key is which of the following?
Answer: B
Correct answer: An attribute that uniquely identifies each row
The primary key distinguishes rows, which is the sense in which a relation is a set. It is chosen from among the candidate keys, and it must be unique, never null, and stable - a value that changes would break every foreign key referring to it.
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Normalization is a formal process for deciding which attributes should be grouped together in a relation.
Answer: A
Correct answer: True
Normalisation is a formal procedure driven by the functional dependencies among attributes, and it decides which attributes belong together in a relation. Because it is formal it can be checked and argued about, which is what distinguishes it from grouping attributes by judgement.
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A transitive dependency is which of the following?
Answer: B
Correct answer: A functional dependency between two or more nonkey attributes.
A transitive dependency arises where one nonkey attribute determines another - a department code determining a department name in an employee relation. The dependent attribute then belongs with the determinant in a relation of its own, and removing such dependencies is what takes a relation from second to third normal form.
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