This document provides an overview of database requirements, design, and development. It discusses the steps in the systems development life cycle as they relate to database projects, including project identification and selection, requirements analysis, logical design, physical design, implementation, and maintenance. Examples of conceptual data modeling and entity relationship diagrams are also presented to illustrate how requirements can be modeled visually.
3. 3
Database development activities during the
systems development life cycle (SDLC)
Project Identification
and Selection
Project Initiation
and Planning
Analysis
Physical Design
Implementation
Maintenance
Logical Design
4. 4
Project Identification & Selection
Purpose: to develop a preliminary
understanding of the business situation that
has caused the request for a new or
enhanced information system.
Deliverable: a formal request for services
5. 5
Project Identification and
Selection
Printing Company: use internet to request
quotes, place orders and check order status
Video Game Store: track customer information,
track customer purchases, maintain inventory
Elementary school After School program:
student records, important information, account
balances
Interpreter’s Organizer: assignment status,
income, costs, taxes
6. 6
Project Identification and
Selection
Groups of 3-5, talk to me if you are thinking about an
individual assignment
I would advise you use either a devise a case study with
your group where you implement a database, or use a
company/scenario that someone in your group is familiar
with. Make sure everyone in the group understands the
scenario
The next step in your group process should be to sit down
and talk about the System Requirement. Make sure
everyone in your group understands what data you want
to get from the database.
9. 9
Overview
Markets a line of clothing and sporting goods via
mail-order catalogs
To remain competitive, company managers want to
create a database to allow Internet customers to:
• Browse the catalog on-line
• Place orders
• Check order status status
10. 10
Information Requirements
System must do all of the following:
• Track information about customers and customer orders
• Track customer orders
• Track inventory information so customers can find out if
an item is available
• Have intranet applications, so Clearwater Traders
personnel can:
• Add, update, and delete inventory items
• Update inventory amounts when new shipments are received
• Modify item prices
12. 12
Constraints
System must be operational by April 2001
System must not require additional purchase
of software/hardware
Other possible constraints? Training employees, …
14. 14
Logical Design
Purpose: to elicit and structure all
information requirements
Deliverables: detailed functional specs for
data, forms, reports, displays, and rules
(logic, algorithms)
15. 15
Principles of Conceptual
Database Design
Identify basic data needs and create
conceptual data models that record
needed data elements and their
relationships
Your local Bank:
How many checking accounts do we have?
How many savings accounts?
How many customers?
How do we get each customer the right
monthly statement?
How do I get a weekly report of overdue loan
payments?
16. 16
Reality and Requirements
Definition
Requires identifying user information
requirements and representing them in a
well-defined model
Model – a representation of reality that retains
only selected details
Database Management System (DBMS)
manages the database so that each user
can record, access, and manipulate the
data that is the “model of reality” of
interest to the user
Requires mapping – associating elements in
one sphere with elements in another sphere
17. 17
Conceptual Data Models
Object-oriented model
Represents real-world entities as objects
rather than as records
• Have their own object identities and attributes
• Participate in relationships
Describes ways of manipulating data that
focuses on the data and the manipulation
(query, computation, update, etc.)
18. 18
Fundamentals
Objects
Important to users in the portion of
reality modeled
• Concrete objects
• People, automobiles, trees, dishwashers, houses,
hammers, books, etc.
• Conceptual objects
• Companies, skills, organizations, product
designs, business transactions, job
classifications, etc.
19. 19
Entity Relationship Diagram
An entity-relationship diagram is a
data modeling technique that creates a
graphical representation of the entities,
and the relationships between entities,
within an information system.
20. 20
The three main components
of an ERD are:
The entity is a person, object, place or
event for which data is collected
The relationship is the interaction
between the entities
The cardinality defines the relationship
between the entities in terms of numbers.
21. 21
The steps involved in
creating an ERD are:
Identify the entities;
Determine all significant interactions;
Analyze the nature of the interactions;
Draw the ERD
22. 22
Synonyms you should know…
Entity = class = relation = table
Attribute = column
Instance = row
rows
columns
table
23. 23
Relationships
MARRIED-MAN IS-MARRIED-TO
MARRIED-WOMAN
MARRIED-MAN = {Adam, David, John} and
MARRIED-WOMAN = {Joan, Linda, Michelle}
and
Adam is-married-to Joan
David is-married-to Linda
John is-married-to Michelle
IS-MARRIED-TO =
{ (Adam, Joan), (David, Linda), (John,
Michelle) }
25. 25
Cardinality
Refers to the maximum number of
instances of 1 object set related to a
single instance of the other object
set
Married
Man
Married
Woman
IS
MARRIED
TO
1 1
Supervisor WorkerSupervises1 *
1:1 relationship
1:M or 1:* relationship
34. 34
Building a Conceptual Data
Model from a Purchase Order
PAYMENT
Check #
Date
ORDER
Number
Tax
TotalDate
VENDOR
Number
Name
Address
* INCLUDES *
1
MADE FROM
*
1
PAID WITH
1
PRODUCT
Stock #
Description
Price
35. 35
Representing Tables
(entities)
Vendor (Number, Name, Address)
Product (Stock #, Description, Price)
Order (Number, Date, Tax, Total)
Payment (Check #, Date)
Attributes are in parentheses
Primary key is underlined.
36. 36
Physical Design
Purpose: to develop all technology &
organizational specs
Deliverables: program & database
structures, technology purchases, physical
site plans and organizational redesigns
37. 37
Implementation
Purpose: to write programs, build data
files, test and install the new system, train
users, and finalize documentation
Deliverables: programs that work
accurately and to specs, documentation
(user and system), and training materials.
38. 38
For Practice...
Identify a potential key value for each of the
following entities:
• Customer (Cust-Name, Cust-ID, Address, Country,
Balance, Month-to-date-payments)
• Sales Rep (Comm%, Office, Manager-ID,
Sales Rep Name, Sales Rep ID)
• Product (Prod-Desc, Mfg-ID, Cost, Price, Prod-ID)
39. 39
For Practice...
For each of the following, draw a data model
showing a relationship between objects and
attributes of the objects. Indicate cardinality.
• Students take classes and get grades in the classes.
• Sections of courses are offered at specified times and in specified
rooms of buildings.
• Employees work a certain number of hours and have a certain
supervisor.
• People subscribe to magazines, and their subscriptions have
beginning and ending dates.