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Review Questions

1.Describe the three-tier ANSI-SPARC architecture. Why do we need mappings between different schema levels? How do different schema definition languages support this architecture?
2.Discuss the advantages and characteristics of the three-tier architecture.
3.Discuss the concept of data independence and explain its importance in a database environment.
4.What is logical data independence and why is it important?
5.What is the difference between physical data independence and logical data independence?
6.How does the ANSI-SPARC three-tier architecture address the issue of data independence?
7.Explain the difference between external, conceptual and internal schemas. How are these different schema layers related to the concepts of physical and logical data independence?
8.Describe the structure of a DBMS.
9.Describe the main components of a DBMS.
10.With a neat sketch, explain the structure of DBMS.
11.What is a transaction?
12.How does the hierarchical data model address the problem of data redundancy?
13.What do you mean by a data model? Describe the different types of data models used.
14.Explain the following with their advantages and disadvantages:
  1. Hierarchical database model

  2. Network database model

  3. Relational database model

  4. E-R data models

  5. Object-oriented data model.

15.Define the following terms:
  1. Data independence

  2. Query processor

  3. DDL processor

  4. DML processor.

  5. Run time database manager.

16.How does the hierarchical data model address the problem of data redundancy?
17.What do each of the following acronyms represent and how is each related to the birth of the network database model?
  1. SPARC

  2. ANSI

  3. DBTG


18.Describe the basic features of the relational data model. Discuss their advantages, disadvantages and importance to the end-user and the designer.
19.A university has an entity COURSE with a large number of courses in its catalog. The attributes of COURSE include COURSE-NO, COURSE-NAME and COURSE-UNITS. Each course may have one or more different courses as prerequisites or may have no prerequisites. Similarly, a particular course may be a prerequisite for any number of courses, or may not be a prerequisite for any other course. Draw an E-R diagram for this situation.
20.A company called M/s ABC Consultants Ltd. has an entity EMPLOYEE with a number of employees having attributes such as EMP-ID, EMP-NAME, EMP-ADD and EMP-BDATE. The company has another entity PROJECT that has several projects having attributes such as PROJ-ID, PROJ-NAME and START-DATE. Each employee may be assigned to one or more projects, or may not be assigned to a project. A project must have at least one employee assigned and may have any number of employees assigned. An employee’s billing rate may vary by project, and the company wishes to record the applicable billing rate (BILL-RATE) for each employee when assigned to a particular project.

By making additional assumptions, if so required, drawn an E-R diagram for the above situation.

21.An entity type STUDENT has the attributes such as name, address, phone, activity, number of years and age. Activity represents some campus-based student activity, while number of years represents the number of years the student has engaged in these activities. A given student may engage in more than one activity. Draw an E-R diagram for this situation.
22.Draw an E-R diagram for an enterprise or an organisation you are familiar with.
23.What is meant by the term client/server architecture and what are the advantages and disadvantages of this approach?
24.Compare and contrast the features of hierarchical, network and relational data models. What business needs led to the development of each of them?
25.Differentiate between schema, subschema and instances.
26.Discuss the various execution steps that are followed while executing users request to access the database system.
27.With a neat sketch, describe the various components of database management systems.
28.With a neat sketch, describe the various functions and services of database management systems.
29.Describe in detail the different types of DBMSs.
30.Explain with a neat sketch, advantages and disadvantages of a centralised DBMS.
31.Explain with a neat sketch, advantages and disadvantages of a parallel DBMS.
32.Explain with a neat sketch, advantages and disadvantages of a distributed DBMS.


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