Transcript Chapter 4: Database Management

Database Management
Chapter 4
Chapter Objectives
• Describe why databases have become so
important to modern organizations
• Describe what database and DBMS are
and how they work
• Explain four emerging database trends:
– Client-server computing
– Object-oriented databases
– Data mining
– Integrating Web applications
Database Management for
Strategic Advantage
• We live in the Information Age
• Information used to make organizations
more productive and competitive
• Databases used to support business
operations
Databases Before the Use of
Computers
• Data kept in books, ledgers, card files,
folders, and file cabinets
• Long response time
• Labor-intensive
• Often incomplete or inaccurate
The Database Approach
• Database-management system (DBMS)
– Interact with the data in databases
• Entity: something you collect data about
• Field: one characteristic of an entity
• Record: collection of fields that describe
one occurrence of an entity
• Entities stored in tables
– One record per row
– One field per column
Sample Data Table
The Database Approach
• DBMS replaced file processing
approach
– Reduced data redundancy
– Reduced program dependence
• Databases typically consist of several
tables
• Tables can be linked together
Key Database Issues
and Activities
• Entering and Querying Data
• Creating Database Reports
Entering and Querying Data
• Use a form for data entry
• Use queries to retrieve information
– Structured Query Language (SQL)
– Query by example (QBE)
Preprinted Form
Application For
Employment
Pine Valley Furniture
Personal Information
Name:Date:
Social Security Number:
Home Address:
City, State, Zip
Home Phone:Business Phone:
U.S. Citizen?If Not, Give Visa No. & Expiration:
Position Applying For
Title:Salary Desired:
Referred By:Date Available:
Education
High School (Name, City, State):
Graduation Date:
Business or Technical School:
Dates Attended:Degree, Major:
Undergraduate College:
Dates Attended:Degree, Major:
Graduate School:
Dates Attended:Degree, Major:
Pine Valley Furniture
Computer-Based Form
QBE Grid
Creating Database Reports
• Report
– A compilation of data organized and
produced in printed format
• DBMS packages include a report writer
• Graphics can be added
• Can be automatically updated by linking
to data
Sample Quarterly Sales Report
Data Structure
• Data model
– A representation of the entities and their
relationships
• Primary key
– An attribute or combination of attributes
– Uniquely identifies each record
Data Type
• Each field is assigned a type
– Text, number, date, etc.
• Data types help the DBMS
– Organize and sort the data
– Do calculations
– Allocate space
• Data dictionary
– A repository of information about the data
– Key fields, data types, valid values, etc.
Database Management
Systems Approaches
• Models of the relationship between
entities in a database
– Hierarchical
– Network
– Relational
The Hierarchical Model
• Models entities in a parent-child
relationship
• One-to-many relationships
– Parent entities can have many child
records
– Each child can have only one parent
• Inadequate model for many databases
– Not always clear which entity is the parent
and which is the child
The Hierarchical Model
The Network Model
• More flexible than the hierarchical
model
• Many-to-many relationships
– Allows multiple children and parents
• Complex databases become too
cumbersome with this model
The Network Model
The Relational Model
• Views entities as two-dimensional
tables
– Records are rows
– Attributes are columns
• Tables can be linked
• Supports one-to-many, many-to-many,
and one-to-one relationships
The Relational Model
Normalization
• A technique used to make complex
databases more efficient
• Break one large table into several
smaller tables
– Eliminates all repeating groups in records
– Eliminates redundant data
Redundant Data
Normalized Data
Associations
• Relationships among the entities in the
data structures
• Three types
– One-to-one
– One-to-many
– Many-to-many
• Relationships set by placing primary key
from one table as foreign key in another
– Creates “acceptable” redundancy
Recent Developments Affecting
Database Design and Use
• Databases and Client-Server Computing
– Server holds the actual database
– Clients hold software to work with the
database
• Object-Oriented Databases (OODBs)
– Treat tables, queries, etc., as reusable
objects
Client/Server Database
Recent Developments Affecting
Database Design and Use
• Data Mining (On-Line Analytical Processing)
– Drill down from summary data to detailed data
– Data Warehouses/Data Marts
• Integrates many large databases into one repository
• Linking Web Site Applications to
Organizational Databases
– Users have Web view to organizational database
– Improves customer contact and service
– Adds security as a concern
Effective Management of
Databases
• Database Administrator (DBA)
– Responsible for the development and
management of an organization’s
databases
• Works with systems analysts on design
• Works with users and managers on
managerial and organizational issues
• Responsible for implementing security
features