What kind of data model is the relational model?. a Explain the following terms in the context of the relational data model2. Relation Attribute Domain Tuple Degree Cardinality b Use the
Trang 1Chapter 3 - Relational Model
Tutorial
1 What kind of data model is the relational model ?
2 (a) Explain the following terms in the context of the relational data model
Relation
Attribute
Domain
Tuple
Degree
Cardinality
(b) Use the Suppliers-Parts database to provide examples of each (see
Appendix 1 of this tutorial)
3 (a) Explain the following terms in the context of the relational data model
Candidate Key
Primary Key
Foreign Key
(b) Use the Suppliers-Parts database to provide examples of each
4 (a) What is the purpose of nulls and what do they represent ?
(b) Is a component of a primary key allowed to accept nulls, why ? (c) What is the term for this constraint ?
(d) Use the Suppliers-Parts database to discuss why it is desirable to enforce
this constraint
5 (a) Describe the constraint called referential integrity
(b) What is the purpose of this constraint ?
Trang 2(c) Use the Suppliers-Parts database to discuss why it is desirable to enforce
referential integrity
6 Examine your “course timetable” and try to answer the following questions:
(b) Are the data and their interpretations kept together ?
(c) Is there any data model behind the data? If so what kind of data model is it
and why ? (d) Are the data structured in a relation and why ?
(e) How would you re-structure the data according to the rules of the relational
data model ?
7 (a) What is a view ?
(b) Discuss the difference between a view and a base relation
(c) Explain what happens when a user accesses a database through a view
Trang 3Appendix 1 Suppliers - Parts Database
Su p p li e r s
Part s
City
Shi p m e n t s