1. Database Requirements and Design

2. The Product: a working system
DATA
PEOPLE
HARDWARE
SOFTWARE
PROCEDURES
The Product: a working system

3. Project Identification
Database development activities during the systems development life cycle (SDLC)
Project Identification
and Selection
Project Initiation
and Planning
Analysis
Logical Design
Physical Design
Implementation
Maintenance

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. 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. 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.

7. Project Initiation and Planning
System Requirements:
Information requirements of the system
Stakeholders
Constraints
Application environment

8. Case Study
The Clearwater Traders Sales Order Database

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. 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

11. Stakeholders
Company management
Clearwater Traders personnel
Customers

12. Constraints System must be operational by April 2001
System must not require additional purchase of software/hardware
Other possible constraints? Training employees, …

13. Application Environment
Access 2000 on networked PCs
Expansion to Web sites using Visual Basic and Personal Web Server

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. 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. 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. 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. 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. 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. 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. 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. Synonyms you should know…
Entity = class = relation = table
Attribute = column
Instance = row
columns
table
rows

23. Relationships MARRIED-MAN IS-MARRIED-TO MARRIED-WOMAN IS-MARRIED-TO =
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) }

24. Representations of a RelationshipIS
MARRIED TO
Married
Man
Married
Woman
(a) The IS MARRIED TO relationship
Adam Joan
David Linda
John Michelle
(b) Some instances of IS MARRIED TO

25. Cardinality
Refers to the maximum number of instances of 1 object set related to a single instance of the other object set IS
MARRIED TO
Married
Man
Married
Woman 1 1
1:1 relationship
Supervises
Supervisor
Worker 1 *
1:M or 1:* relationship

26. Basic E-R Notation

27. Sample E-R Diagram

28. E-R model with only the necessary entities

29. Primary key attribute

30. Composite key attribute

31. Relationship types and instances
(a) Relationship type “Completes”

32. Cardinality constraints
(a) Relationship showing maximum cardinality only.

33. Cardinality constraints
(b) Relationship showing max & min cardinality

34. Building a Conceptual Data Model from a Purchase Order
PAYMENT
Check #
Date
VENDOR
Number
Name
Address 1
MADE FROM * 1
PAID WITH
PRODUCT
Stock #
Description
Price
ORDER
Number
Tax
Total
Date
* INCLUDES *

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. Physical Design
Purpose: to develop all technology & organizational specs
Deliverables: program & database structures, technology purchases, physical site plans and organizational redesigns

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. 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. 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.