1. All superkeys are candidate keys - FALSE. A superkey is a set of attributes within a table whose values can be used to uniquely identify a tuple. A superkey can have additional attributes that do not need to be there. On the other hand, a candidate key is a minimal set of attributes necessary to identify a tuple uniquely. Therefore, while every candidate key is a superkey, not all superkeys are candidate keys.

2. All candidate keys are superkeys - TRUE. As mentioned above, a candidate key is a minimal set of attributes necessary to identify a tuple uniquely. This means that every candidate key is a superkey, but the reverse is not true.

3. A foreign key can be a primary key - TRUE. A foreign key is a field (or collection of fields) in one table, that is used to link two tables together. The foreign key in one table points to the primary key in another table. However, it is possible for a foreign key to also be a primary key, depending on the database design.

4. All superkeys are primary keys - FALSE. A primary key is a specific choice of a minimal superkey. Therefore, while every primary key is a superkey, not all superkeys are primary keys.

Question

1. All superkeys are candidate keys - FALSE. A superkey is a set of attributes within a table whose values can be used to uniquely identify a tuple. A superkey can have additional attributes that do not need to be there. On the other hand, a candidate key is a minimal set of attributes necessary to identify a tuple uniquely. Therefore, while every candidate key is a superkey, not all superkeys are candidate keys.

2. All candidate keys are superkeys - TRUE. As mentioned above, a candidate key is a minimal set of attributes necessary to identify a tuple uniquely. This means that every candidate key is a superkey, but the reverse is not true.

3. A foreign key can be a primary key - TRUE. A foreign key is a field (or collection of fields) in one table, that is used to link two tables together. The foreign key in one table points to the primary key in another table. However, it is possible for a foreign key to also be a primary key, depending on the database design.

4. All superkeys are primary keys - FALSE. A primary key is a specific choice of a minimal superkey. Therefore, while every primary key is a superkey, not all superkeys are primary keys.

Knowee AI · Accepted Answer

1. All superkeys are candidate keys - FALSE. A superkey is a set of attributes within a table whose values can be used to uniquely identify a tuple. A superkey can have additional attributes that do not need to be there. On the other hand, a candidate key is a minimal set of attributes necessary to identify a tuple uniquely. Therefore, while every candidate key is a superkey, not all superkeys are candidate keys.

2. All candidate keys are superkeys - TRUE. As mentioned above, a candidate key is a minimal set of attributes necessary to identify a tuple uniquely. This means that every candidate key is a superkey, but the reverse is not true.

3. A foreign key can be a primary key - TRUE. A foreign key is a field (or collection of fields) in one table, that is used to link two tables together. The foreign key in one table points to the primary key in another table. However, it is possible for a foreign key to also be a primary key, depending on the database design.

4. All superkeys are primary keys - FALSE. A primary key is a specific choice of a minimal superkey. Therefore, while every primary key is a superkey, not all superkeys are primary keys.

Which of the following statements are TRUE?All superkeys are candidate keysAll candidate keys are superkeysA foreign key can be a primary keyAll superkeys are primary key

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