COMP 266 Lecture Notes - Lecture 3: Systems Development Life Cycle, Rapid Application Development, Relational Model
30 Jun 2018
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C O M P U T E R S C I E N C E 3 7 8 : I N T R O D U C T I O N T O D A T A B A S E M A N A G E M E N T
Assignment 1
Total: 100 marks
Weight: 10% of your final grade
Due: After you have completed Unit 3.
Answer all of the following questions, and upload your completed work here.
Question 1 (15 marks)
Answer the following questions (250 words max/question).
a. Explain the concept of program-data independence, and explain how it is achieved in the database
approach.
In file processing system, the file descriptions are stored within each database application program that
accesses a given file. Since the program contains a detailed file description for these files, any change occur
to a file structure requires changes to the file descriptions for all programs that access the file.
The program-data independence is the separation of these data descriptions from the application programs
that use the data.
This can be achieved by storing the data descriptions in a central location called repository. This property of
database systems allows an organization’s data to change and develop gradually within limits without
changing the application programs that process the data.
Older data models and database management software was not built on program-data independence
concept. Relational model and all newer object oriented models uses this concept.
b. Briefly contrast and compare the following development approaches: the systems development life cycle
and the prototyping methodology.
System Development Life Cycle (SDLC) is set of steps that a team of IT professionals (such as programmers
and database designers) follow to develop, maintain or replace information system. There are many
variations on SDCL and number of phases may be from 3 to 20. In short SDCL is a cycle of following 5
phases:
1. Planning
2. Analyses
3. Design
4. Implementation
5. Maintenance
Development process is circular and some steps may overlap in time or may be conducted in parallel.
As we can see, SDLC is very structured and methodical approach. Main weakness of this approach is that
sometimes it takes too much time. From that reason, organizations use RAD (Rapid Application Development).
Prototyping is one of the most popular RAD methods. Prototyping is iterative process in which requirements are
converted to a working system. This system is continually revised through close work between analysts and users.
Main phases in prototyping are:
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Answer all of the following questions, and upload your completed work here. Answer the following questions (250 words max/question): explain the concept of program-data independence, and explain how it is achieved in the database approach. In file processing system, the file descriptions are stored within each database application program that accesses a given file. Since the program contains a detailed file description for these files, any change occur to a file structure requires changes to the file descriptions for all programs that access the file. The program-data independence is the separation of these data descriptions from the application programs that use the data. This can be achieved by storing the data descriptions in a central location called repository. This property of database systems allows an organization"s data to change and develop gradually within limits without changing the application programs that process the data. Older data models and database management software was not built on program-data independence concept.
