Keys in DDMS Questions and Answers

Keys in DDMS

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Question List:

1. All candidate keys are superkeys, whereas all superkeys are not candidate keys. Justify this statement with a suitable example.

2. Illustrate the difference between primary key and foreign key.

3. What do you mean by a self-referencing foreign key? Explain with the help of an example.

4. Can a relation have more than one foreign key? Explain with the help of an example.

5. Explain integrity constraints. Describe their importance.

6. Differentiate between a superkey, a candidate key and a primary key.