Chapter 6 – Data Design

Question 1

Database Management System (DBMS)

Answer 1

• Collection of tools, features and interfaces that enables users to:
	- Add
	- Update
	- Manage
	- Access
	- Analyze
		~ The contents of a set data
• Interface between a:
	- Database
	- Users
		~ Who need to access the data
• Components:
	- Interface for:
		~ Users
		~ Database administrators
		~ Related systems
	- Data manipulation language
	- Schema
	- Physical data repository

Question 2

Schema

Answer 2

• The complete definition of a database including descriptions of all:

- Fields
- Tables
- Relationships

Question 3

Subschema

Answer 3

• Can be defined one or more
• View of the database used by one or more systems or users
• Defines only those portions of the database that a particular system or user needs is allowed to access

Question 4

Physical Data Repository

Answer 4

• Data dictionary is transformed into a:
- Physical data repository also contains the schema and subschemas
• Physical repository:
- Centralized or distributed at several locations
• Database standards:
- Open database connectivity (ODBC)
- Java database connectivity (JDBC)

Question 5

Characteristics of Web-Based Design

Answer 5

• Global access
	- The internet enables worldwide access using existing infrastructure
• Ease of use
	- Web browsers provides a familiar interface that is:
		~ User-friendly
		~ Easily learned
• Multiple platforms
• Cost effectiveness
• Security issues
• Adaptability issues

Question 6

Internet Terminology

Answer 6

• Intranet
• Extranet
• Clients
• Servers
• Protocols

Question 7

Connecting a Database to the Web

Answer 7

• Database must be connected to the internet or intranet
- Middleware
- Example:
~ Adobe ColdFusion

Question 8

Data Security

Answer 8

• Web-based data:

- Totally secure
- Easily accessible to authorized users

Question 9

Data Design Terminology (*)

Answer 9

• Definitions
	- Entity
	- Table or file
	- Field or Attribute
		~ Single characteristic about an entity
	- Record or Tuple

Question 10

Key Fields

Answer 10

• Primary
• Candidate
• Foreign
• Secondary keys

Question 11

Primary key

Answer 11

Uniquely identifies a particular member of an entity
• Combination key
• Composite
• Key
• Concatenated key
• Multi-valued key

Question 12

Candidate key

Answer 12

• Could serve as the primary key
- Nonkey field
~ Not a primary key and not a candidate key

Question 13

Foreign key

Answer 13

• Primary key in one table

* Foreign key in another table

Question 14

Secondary key

Answer 14

Can be used to access or retrieve records

Question 15

Referential Integrity

Answer 15

• Validity checks:
- Can help avoid data input errors
• In a relational database:
- Means that a foreign key value cannot be entered in one table unless it matches an existing primary key in another table
• Example:
- Preventing you from entering a customer order in an order table unless that customer already exists in the customer table
• Orphan

Question 16

Entity-Relationship Diagrams (ERD)

Answer 16

• An entity is a person, place, thing or event
- For which data is collected and maintained
• ERD:
- Provides an overall view of the system
- A blue print for creating the physical data structure

Question 17

Normalization

Answer 17

• A process of creating table designs by:
	- Assigning specific fields or attributes
• Table design
• Involves 4 stages:
	- Unnormalized design (UNF)
	- First normal form (1NF)
	- Second normal form (2NF)
	- Third normal form (3NF)
• Standard Notation Format

Question 18

Database Models

Answer 18

• Relational Databases
- New entities and attributes can be added at any time
~ Without restructuring the entire database
• Object-Oriented Databases
- Natural extension of the object-oriented analysis process
- Object Database Management Group (ODMG)
- Each object has a unique object identifier

Question 19

Data Storage and Access

Answer 19

• Involves strategic business tools
• Strategic tools for data storage and access
• Logical and Physical Storage (*)
• Data Storage Formats

Question 20

Data warehouse - Dimensions of characteristics (*)

Answer 20

• Integrated collection of data that can support:

- Management analysis
- Decision making

Question 21

Data mart (*)

Answer 21

• Serve the needs of a specific department
• Each data mart includes only:
- The data that users in that department require to perform their jobs

Question 22

Data mining (*)

Answer 22

• Looks for:
- Meaningful data patterns and relationships
• Help companies identify:
- Potential customers based on their prior purchases
• Focuses on:
- Methods of obtaining valuable business knowledge from a data warehouse

Question 23

Goal of data mining

Answer 23

• Increase:
	- Average pages viewed per session
	- Checkouts per visit
	- Number of referred customers
	- Average profit per checkout
• Reduce:
	- Clicks to close
• Clickstream storage – market basket analysis

Question 24

Logical and Physical Storage (*)

Answer 24

• Logical storage
	- Data that a user can:
		~ View
		~ Understand
		~ Access
			\+ Characters
			\+ Date element / Data item
			\+ Logical record
• Physical storage
	- Hardware-related
		~ Physical record / block
		~ Buffer
		~ Blocking factor

Question 25

Data Storage Formats

Answer 25

• Binary digits
	- Binary storage format
	- Integer format
	- Long integer
		~ Exists for efficient storage of exceedingly long numbers
• Bit
• Byte
• EBCDIC & ASCII
• Unicode