Why do we designate one of the candidate keys of a relation to be the primary key?

5.1Define the following terms as they apply to the relational model of data:

domain,

attribute,

n-tuple,

relation schema,

relation state,

degree of a relation,

relational database schema, and relational database state.

5.2. Why are tuples in a relation not ordered?

5.3. Why are duplicate tuples not allowed in a relation?

5.4. What is the difference between a key and a superkey?

5.5. Why do we designate one of the candidate keys of a relation to be the primary key?

5.6. Discuss the characteristics of relations that make them different from ordinary tables and files.

5.7. Discuss the various reasons that lead to the occurrence of NULL values in relations.

5.8. Discuss the entity integrity and referential integrity constraints. Why is each considered important?

5.9. Define foreign key. What is this concept used for?

5.10. What is a transaction? How does it differ from an Update operation?