Which of the following statements is true?Group of answer choicesEvery super key is a candidate key.An alternate key is a super key with redundant attributes.A composite key cannot be a primary keyEvery candidate key is a super key.
Question
Which of the following statements is true?Group of answer choicesEvery super key is a candidate key.An alternate key is a super key with redundant attributes.A composite key cannot be a primary keyEvery candidate key is a super key.
Solution
The statement "Every candidate key is a super key" is true.
Here's why:
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A super key is a set of one or more columns (attributes) that can uniquely identify a record in a table. It may contain additional attributes that are not necessary for unique identification.
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A candidate key is a minimal super key, meaning it is a set of columns such that the set is still a super key even if we remove any column from the set. It does not contain any unnecessary attributes.
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Therefore, every candidate key is a super key because it can uniquely identify a record. However, not every super key is a candidate key because a super key may contain additional unnecessary attributes.
The other statements are false because:
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Not every super key is a candidate key because a super key can have redundant attributes.
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An alternate key is not a super key with redundant attributes. An alternate key is a candidate key that is not the primary key.
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A composite key can be a primary key. A composite key is a key that consists of two or more attributes that uniquely identify an entity occurrence. If chosen as the method to uniquely identify an entity occurrence, it becomes the primary key.
Similar Questions
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