Download Database

3
Technology Briefing
Database Management
“Modern organizations are said to be drowning
in data but starving for information”
p. 509
Information Systems Today: Managing in the Digital World
TB3-1
Learning Objectives
Information Systems Today: Managing in the Digital World
TB3-2
Learning Objectives
Information Systems Today: Managing in the Digital World
TB3-3
Database Management for
Strategic Advantage
• Database technology is vital to an
•
organization’s success
Variety of information collected and stored
o Stock prices
o Potential customers
o Credit ratings of wholesalers
o Etc.
Information Systems Today: Managing in the Digital World
TB3-4
Database Management for
Strategic Advantage (II)
• Database technology used for:
o Gathering and storing customer information
o Custom-tailoring catalogs and mailings
o Fueling electronic commerce
o Etc.
Information Systems Today: Managing in the Digital World
TB3-5
Learning Objectives
Information Systems Today: Managing in the Digital World
TB3-6
Database Foundations
• Then:
o Card catalogs
o File cabinets
• Now:
o DBMS
• Create
• Store
• Organize
• Retrieve data
o E.g., Microsoft Access
Information Systems Today: Managing in the Digital World
TB3-7
Database
• Database
o Collection of related
data organized in a
way to facilitate
searches
o Entities
• Something you collect
•
data about
E.g.: people, books
Information Systems Today: Managing in the Digital World
TB3-8
Record
• Contains data
about a single
entity
o Similar to catalog
card
Information Systems Today: Managing in the Digital World
TB3-9
Attributes
• Specific characteristic
describing the entities
o E.g.: name and social
security number are
attributes of a person
Information Systems Today: Managing in the Digital World
TB3-10
Example: Entity Student
• Entity represented as a table, with rows as records and
columns as attributes
Information Systems Today: Managing in the Digital World
TB3-11
Advantages of the Database Approach
1. Program-data independence
2. Minimal data redundancy
3. Improved data consistency
4. Improved data sharing
5. Increased productivity of application
development
Information Systems Today: Managing in the Digital World
TB3-12
Advantages of the Database
Approach (II)
6. Enforcement of standards
7. Improved data quality
8. Improved data accessibility
9. Reduced program maintenance
Information Systems Today: Managing in the Digital World
TB3-13
Cost and Risks of the Database Approach
1. New, specialized personnel
2. Installation and management cost and
complexity
3. Conversion costs
4. Need for explicit backup and recovery
5. Organizational conflict
Information Systems Today: Managing in the Digital World
TB3-14
Effective Management of
Databases
• Database Administrator (DBA)
o Responsible for development and
management of databases
• Works with system analysts and programmers
• Works with users and managers
• Implements security features
• Grants access rights
o One of the key actors in creating a
successful database
Information Systems Today: Managing in the Digital World
TB3-15
Entering Data
• Forms
o Enter data about a record
o Field in a form corresponds to attribute in a
record
o Used to add, modify, or delete data
Information Systems Today: Managing in the Digital World
TB3-16
Example: Computer-Based Form
Information Systems Today: Managing in the Digital World
TB3-17
Querying Data
• Query: used to retrieve information
• Structured Query Language (SQL)
o Example: Display students who earned an “A”
o Writing SQL queries can become very complex
Information Systems Today: Managing in the Digital World
TB3-18
Query by Example
• Simpler than
•
•
SQL
Drag-anddrop features
Construct a
sample of the
data we would
like to see
Information Systems Today: Managing in the Digital World
TB3-19
Creating Database Reports
• Report
o Compilation of data from the database
• Report generators
o Retrieve, manipulate, and display data
• Example
o Quarterly sales for
a restaurant
• Adding
• Grouping
Information Systems Today: Managing in the Digital World
TB3-20
Database Design
• Data need to be organized for retrieval
and analysis
o Key elements of a database
• Data
• Structure
• Data model
o A map or a diagram representing entities
and their relationships
Information Systems Today: Managing in the Digital World
TB3-21
Example: Entities and Their Attributes
Information Systems Today: Managing in the Digital World
TB3-22
Identifying Records
• Uniquely identifying records:
o Primary Key
• Unique identifier
• E.g.: Student ID number, social security number
o Combination primary key
• Combination of two or more attributes
• E.g.: identifying a student’s grade for a particular class for a
particular term
• Identifying records that share a common value
o Secondary Key
• Attribute not used as a primary key
• E.g., Major
Information Systems Today: Managing in the Digital World
TB3-23
Associations
• Used to relate information between tables
• Needed to retrieve information
• Example: Basketball league database
Information Systems Today: Managing in the Digital World
TB3-24
Example: Basketball League
•
•
•
Each table
contains
important data
No way to learn
which team plays
in a specific
stadium
Need to make
associations
Information Systems Today: Managing in the Digital World
TB3-25
Example: Basketball League
•
Foreign keys
o Attributes used
to link tables
o Primary key in
one table,
foreign key in
another
o Need to create
additional
entity for
many-to-many
relationships
Information Systems Today: Managing in the Digital World
TB3-26
Entity-Relationship Diagram
• Used to show associations between entities
• Important when designing complex databases
o Entities: represented by boxes
o Relationships: represented by lines
Associations
Information Systems Today: Managing in the Digital World
TB3-27
The Relational Model
• Primary DBMS approach (RDBMS)
• 3 dimensions
o Entities represented
as 2-dimensional tables
• Rows = records
• Columns = attributes
o Tables joined based
on common columns
(3rd dimension)
• Good design eliminates redundancy
Information Systems Today: Managing in the Digital World
TB3-28
Data Redundancy
• Problematic if an attribute has to be changed
o Need to change in multiple locations
• E.g., instructor’s phone number
Information Systems Today: Managing in the Digital World
TB3-29
Normalization
• Eliminate unnecessary redundancy
o Create separate tables
o Data only
needs to
be changed
in a single
location
Information Systems Today: Managing in the Digital World
TB3-30
Data Dictionary
• Document that specifies what data needs
•
to be entered
o Attribute name
o Key or not
o Data type
o Valid values
Can be used to enforce business rules
Information Systems Today: Managing in the Digital World
TB3-31
Linking Website Applications to
Organizational Databases
• Users can access a variety of data via a
company’s web site
o Web services help in integration of
databases, regardless of physical location
• Need for adequate systems performance
• Get understanding of customer behavior
Information Systems Today: Managing in the Digital World
TB3-32