CMSC 508
Database Theory
Homework 7

Due: April 13

There are other database models besides the relational model. These include the network model, the heirarchical model, object-oriented databases, xml databases, No SQL databases. This homework and the next investigate some of these.

In order for a model to be a "database system" it should provide the following:

1. a standard structure for storing the data
2. a query language which can be used to retrieve information from any database of that model.
3. data independence

1. Do some research and answer the following questions:

a) What is the standard structure for storing data in the object-oriented model?
b) What is the query language for the object-oriented model?
c) Does an object-oriented database provide data independence?
d) Would you consider an object-oriented database system to truly be a database?

2. Answer a-d above for the heirarchical database.

The remaining questions are about the IMS heirarchical database system, and use the following logical structure.

This figure represents an IMS database that contains information about published papers in a number of selected subject areas. The segments contain the following fields:

Subject: subject classification number (unique), name of subject

Paper: title, abstract, number of pages

Details: publishing company, journal name, volume number, issue number, date of publication (note that a given paper may be published several times in several different places)

Author: author name, address (note that a given paper may have several authors)

3. Define an appropriate DBD for this information.

4. Define a PCB (all segments and fields sensitive) for the publications database.  This PCB is to be used for both retrieval and update operations.

5. Write psuedocode programs including DL/I operations for the following:

(a) List the names of all the journals that have published papers written on the subject of "Information Retrieval". Do not worry about removing duplicates.

(b) List all papers for which Parker is one of the authors

(c) List all subjects on which the Bradbury Publishing Company has published a paper