CH 04

Chapter
Chapter 44
Database
Management
Systems
What is a Database
Management System (DBMS)?
 Database
• An organized collection of related data
 Database Management System
• Comprises programs to store, retrieve, and
otherwise manage a computerized
database and to provide interfaces to
application programs and to non-
programming users
Chapter 4 Slide 2
Functions of A Database Management
System
 Storing and Retrieving Data
• The database sees the physical view of
the data
How the data are compressed and formatted,
which data are stored near each other, and
which indexes are created to simplify and
speed finding data on the storage medium
Chapter 4 Slide 3
Functions
FunctionsofofAADatabase
Database Management
Management System
System
 Storing and Retrieving Data
• The database presents a logical view to
the user and programmer
Organizes and presents data elements in ways
that managers and other users find helpful
Chapter 4 Slide 4
Functions
Database Management
Management System
System
 Managing Metadata
• Metadata are data about data in the
database
• Example
The fact that a company's invoice numbers are
six digits long, with the first digit being either a
1 or 3
Chapter 4 Slide 5
Functions
Database Management
Management System
System
 Limiting and Controlling Redundant
Data in Multiple Systems
• Companies often collect and store the
same data in two or more different
information systems
Chapter 4 Slide 6
Functions
Database Management
Management System
System
 Supporting Simultaneous Data

Sharing
• Concurrency control
Describes the proper management of
simultaneous attempts to update a database by
multiple users or multiple software programs
Chapter 4 Slide 7
Functions
Database Management
Management System
System
 Providing Transaction Atomicity
• The concept that a transaction cannot be
split into smaller parts
• If systems fails in midst of transaction,
system is restored as if the entire
transaction completed or no part of it
completed
Chapter 4 Slide 8
Functions
Database Management
Management System
System
 Providing Backup and Recovery
Services
• Databases cannot be backed up like files
because they are too large and in constant
use
• Backup techniques include
Operating in parallel on two storage devices
Use of temporary database during backup
Chapter 4 Slide 9
System
 Providing Authorization and Security
Services
• Most DBMSs can limit who has access to
specific data
• DBMS can create limited views of data so
that users can see only what they are
authorized to see
Chapter 4 Slide 10
System
 Enforcing Business Rules
• A DBMS enforces rules that ensure related
data are logically consistent
Chapter 4 Slide 11
Database Applications
 Support for Application Software

• Providing a common data repository
• Performing support functions, such as data
storage, metadata storage, concurrency
control, and other DBMS functions that
would otherwise have to be performed by
the application software
Chapter 4 Slide 12
 Data Warehouse
• An enterprise-wide database designed to
support business intelligence and
management decision making rather than
operational needs
Chapter 4 Slide 13
 Data Mart
• Provides summary and historical data for
business intelligence and decision making
for a single department or division rather
than an entire organization
Chapter 4 Slide 14
 Serving Dynamic Web Pages

• Allows Web content managers to change
Web pages by updating a database
• Content management
Software designed to ease the development of
Web pages by fields from a database into a
Web page template
Chapter 4 Slide 15
Developing Databases through Data
Design
 Data Design
• The process of identifying and formalizing
the relationships among the elements of
data that will form an organization's
database
Chapter 4 Slide 16
Design
[Insert Figure 4-4 here]
Chapter 4 Slide 17
Design
 Entity-Relationship (E/R) Model
• The E/R model offers a pictorial way of
showing the interrelationships among
various types of data
Chapter 4 Slide 18
The Entity-
Relationship Model
Figure 4-5 Chapter 4 Slide 19

Technological Underpinnings
 Distribution Architecture
• Refers to how the organization distributes
data and database processing physically
among the computers in a network
Chapter 4 Slide 20
 Types of Distribution Architectures

• Decentralized architecture
Involves no data sharing
• Centralized architecture
Has a single DBMS running on a single
computer and maintaining data centrally
Chapter 4 Slide 21

• Client/Server architecture
Divides the functions of a DBMS among
connected computers on a network, while
centralizing permanent storage for all data on a
computer called the database server
Chapter 4 Slide 22

• Distributed architecture
Distributes both data and processing
Treats data as a single database, giving every
database client and every server access to all
the data in the database no matter where it
resides
• Mixed architecture
Utilizes more than one architecture
Chapter 4 Slide 23
 Database Models
• Relational model
A table represents a file with rows called tuples
and columns called attributes
Chapter 4 Slide 24
[Insert Figure 4-8 here]
Chapter 4 Slide 25
 Database Models
• Object model
Derives from object-oriented programming
Object-oriented DBMSs store objects and
object-class metadata
Chapter 4 Slide 26
 Database Models
• XML model
A language used to mark and identify
components of Web-based transaction
documents
Chapter 4 Slide 27
 Database Models
• Network model
Builds a tighter linkage between elements of
data
• Hierarchical model
A precursor to the network model, as a network
model with additional restrictions
Views data as organized in a logical hierarchy
Chapter 4 Slide 28
Managing the Data Resource
 Data Administrator
• Concerned with integrity of data, data
redundancy, access controls, and rules
about data relationships
 Database Administrator (DBA)
• Oversees functioning of particular DBMS
• More technical than data administrator
Chapter 4 Slide 29
End
End of
of
Chapter
Chapter 44
Database
Management
Systems

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Chapter

 Supporting Simultaneous Data

 Support for Application Software

 Serving Dynamic Web Pages

[Insert Figure 4-4 here]

Figure 4-5 Chapter 4 Slide 19

 Types of Distribution Architectures

 Types of Distribution Architectures

 Types of Distribution Architectures

[Insert Figure 4-8 here]

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