Database SDLC

Intro to Information Systems*
*
Information Systems Architecture
This is a blueprint for organization’s desired information systems structure
It consists of:
Data Network – topology diagram
Rules - Reasons for events and e.g. decision tables
Compiled by L. Mutanu
The StayHome case study
It rents out videos to its members.
The first branch of StayHome was established in 1982 in Seattle.
The company has now grown and has many branches throughout the United States.
StayHome staff registration form
StayHome however keeps data about its staff using the Ms word form showed below.
CH2 THE DATABASE DEVELOPMENT PROCESS
Every branch keeps a list of staff members as shown below
Additionally a list of the videos kept in a branch is also maintained
When a new member joins StayHome they fill in the registration form below
A list of members in the branch is also maintained
When a member rents a video the following information is kept
You have been asked to develop a DBMS for Stay Home.
Approaches to Database Development
Detailed, well-planned development process
Defines database during development of initial prototype
Repetition of implementation and testing activities with new prototype versions
Systems Development Life Cycle
Planning
Analysis
Defines the major aims of the database system.
specifies, in general terms, the work to be done, the resources with which to do it, and the money to pay for it all.
Database activity–conceptual data modeling (What Data?)
Planning
Analysis
StayHome case study – Analysis
Branches
Staff
Video
Members
Rentals
Suppliers
Database activity– design transactions, forms, displays, views, data integrity and security
How is data manipulated?
What activities will be conducted on the data?
Maintaining/Edit – Enter, Update and Delete
Querying – Searching for analysis
Database activity– physical database design (define database to DBMS, physical data organization, database processing programs)
Planning
Analysis
CASE Tools?
Database activity – writing, coded programs, documentation, installation and conversion
Planning
Analysis
Planning
Analysis
Prototyping Database Methodology
Database Schema
The schema of a database system is its structure. In a relational database, the schema defines the tables, the fields, relationships, etc.
The Three-Schema Architecture is the most popular. It contains:
External Schema - User Views. Determined from business- function/data entity matrices. It is a subsets of Conceptual Schema
Conceptual Schema – Data administrators view. Combines different external views into a single view.
Internal Schema – This is the underlying design and implementation . It consists of two different schemas:
Logical structures – Shows the data structure
Physical structures – Shows how the data is stored
Data Independence
Logical Data Independence - Refers to immunity of external schemas to changes in conceptual schema. Conceptual schema changes (e.g. addition/removal of entities) should not require changes to external schema or rewrites of application programs.
Physical Data Independence - Refers to immunity of conceptual schema to changes in the internal schema. Internal schema changes (e.g. using different file organizations, storage structures/devices). Should not require change to conceptual or external schemas.
The Three-Level Architecture offers the following benefits:
All users should be able to access same data.
A user’s view is immune to changes made in other views.
Users do not need to know physical database storage details.
Developing three-schema architecture for a database
StayHome case study – External Schema
Gather more details on user views to create users’ requirements specification, which describes data to be held in database and how data is to be used.
Which are the different users of the system?
What data do they want?
What can they do with the data; Edit, Query or simply view?
Overall Manager
Branch supervisors
CRUD Matrix
Collect general requirements to create the system - systems specification
Describes features to be included in new database system such as networking, shared access, performance, and security requirements.
Multi-User DBMS Architectures
1. Teleprocessing
Traditional architecture. Was a single mainframe with a number of terminals attached.
2. File-Server
File-server is connected to several workstations across a network. The database resides on file-server. DBMS and applications run on each workstation.
Disadvantages include:
Concurrency control more complex.
3. Client-Server
Client manages and runs applications.
Advantages include:
increased performance;
reduction in communication costs;
Three-tiered Client-Server Database Architecture
StayHome case study – DBMS Architecture

Documents

Database SDLC