1. Conceptual Database Design
Dale-Marie Wilson, Ph.D.

2. Database Design Methodology
Structured approach that uses procedures, techniques, tools, documentation aids to support and facilitate design process
Three main phases
Conceptual database design
Logical database design
Physical database design

3. Database Design Methodology
Conceptual database design
Process of constructing model of data used in an enterprise, independent of all physical considerations
Logical database design
Process of constructing model of data used in enterprise based on specific data model (e.g. relational)
Independent of particular DBMS and other physical considerations
Physical database design
Process of producing description of implementation of database on secondary storage
Describes base relations, file organizations, and indexes
Attempts to achieve efficient access to data, integrity constraints and security measures

4. Critical Success Factors in Database Design
Work interactively with users
Follow structured methodology throughout data modeling process
Employ data-driven approach
Incorporate structural and integrity considerations into data models
Combine conceptualization, normalization, and transaction validation techniques into data modeling methodology

5. Critical Success Factors in Database Design
Use diagrams to represent data models
Use Database Design Language (DBDL) represent additional data semantics
Build data dictionary to supplement data model diagrams
Be willing to repeat steps

6. Overview Database Design Methodology
Conceptual database design
Step 1 Build conceptual data model
Step 1.1 Identify entity types
Step 1.2 Identify relationship types
Step 1.3 Identify and associate attributes with entity or relationship types
Step 1.4 Determine attribute domains
Step 1.5 Determine candidate, primary, and alternate key attributes

7. Overview Database Design Methodology
Step 1 Build conceptual data model (continue)
Step 1.6 Consider use of enhanced modeling concepts (optional step)
Step Check model for redundancy
Step Validate conceptual model against user transactions
Step Review conceptual data model with user

8. Overview Database Design Methodology
Logical database design for the relational model
Step 2 Build and validate logical data model
Step 2.1 Derive relations for logical data model
Step 2.2 Validate relations using normalization
Step 2.3 Validate relations against user transactions
Step 2.4 Define integrity constraints

9. Overview Database Design Methodology
Step 2 Build and validate logical data model (continue)
Step 2.5 Review logical data model with user
Step 2.6 Merge logical data models into global model (optional step)
Step 2.7 Check for future growth

10. Overview Database Design Methodology
Physical database design for relational database
Step 3 Translate logical data model for target DBMS
Step 3.1 Design base relations
Step 3.2 Design representation of derived data
Step 3.3 Design general constraints

11. Overview Database Design Methodology
Step 4 Design file organizations and indexes
Step 4.1 Analyze transactions
Step 4.2 Choose file organization
Step 4.3 Choose indexes
Step 4.4 Estimate disk space requirements

12. Overview Database Design Methodology
Step 5 Design user views
Step 6 Design security mechanisms
Step 7 Consider the introduction of controlled redundancy
Step 8 Monitor and tune the operational system

13. Step 1: Build Conceptual Data
Model comprised of:
Entity types, relationship types, attributes and attribute domains, primary and alternate keys, and integrity constraints
Step 1.1 Identify entity types
To identify required entity types
Step 1.2 Identify relationship types
To identify important relationships that exist between entity types
Step 1.3 Identify and associate attributes with entity or relationship types
To associate attributes with appropriate entity or relationship types and document details of each attribute
Step 1.4 Determine attribute domains
To determine domains for attributes in data model and document details of each domain

14. Step 1: Build Conceptual Data
Step 1.5 Determine candidate, primary, and alternate key attributes
To identify candidate key(s) for each entity
If more than one candidate key => choose one as primary key
Step 1.6 Consider use of enhanced modeling concepts (optional step)
To consider use of enhanced modeling concepts
Specialization / generalization, aggregation, and composition
Step 1.7 Check model for redundancy
To check for presence of redundancy in model
Remove if exists
Step 1.8 Validate conceptual model against user transactions
To ensure conceptual model supports required transactions
Step1.9 Review conceptual data model with user
To review conceptual data model with user to ensure model is ‘true’ representation of data requirements of enterprise

15. Extract - data dictionary of entities for Staff user views of DreamHome

16. 1st Version - ER diagram of Staff user views of DreamHome

17. Extract - data dictionary of relationships for Staff user views of DreamHome

18. Extract - data dictionary of attributes for Staff user views of DreamHome

19. ER diagram of Staff user views of DreamHome

20. Example – Removal of redundant relationship called Rents

21. Example of non-redundant relationship FatherOf

22. Question
Your job is to design a database for the XYZ Company.  They are part suppliers.  Their customers order parts from them and they get the parts, or items, from various suppliers.  An order may consists of several items.  Each item, or part, has an unique identifier

23. Suppliers Part Order Customer Consists Salesperson M 1 M places M
Parts M M
Supply
controls
Consists 1 1
Salesperson
Suppliers
Suppliers
supplierID
companyName
phoneNo
address1
address2
city
state
zip
contactName
Part
partID
price
description
qty
supplierID
Order
orderID
customerID
ssn
totalPrice
orderDate
Customer
customerID
fName
middleI
lName
address1
address2
city
state
zip
Consists
partID
orderID
qty
Salesperson
ssn
fName
middleI
lName
address1
address2
city
state
zip
dateOfBirth

24. Example – EasyDrive School of Motoring
See handouts.