2. Outline
Database Introduction
An Example
Characteristics of the Database
Actors on the Scene
Advantages of using the DBMS approach
3. Database Examples
Database is involved like everywhere in our world
For example:
If we go to bank to deposit or withdraw
Make hotel and airline reservation
Purchase something on line
Buy groceries in supermarkets
4. Database Applications
These examples are what we called traditional
database applications
(First part of book focuses on traditional applications)
More Recent Applications:
YouTube
iTunes
Geographic Information Systems (GIS)
Data Warehouses
Many other applications
5. Database can be any size and
complexity
For example:
A list of names and address
IRS
(assume it has 100 million taxpayers and each
taxpayer file 5 forms with 400 characters of
information per form=800Gbyte)
Amazon.com
(15 million people visit per day; about 100 people are
responsible for database update)
6. Database System
Database:
A collection of related data.
Data:
Known facts that can be recorded and have an
implicit meaning.
Database Management System (DBMS):
A software package/system to facilitate the
Define, Construct, Manipulate and Share functions
of a computerized database.
7. Typical DBMS Functionality
Define a particular database in terms of its data types,
structures, and constraints
Construct or Load the initial database contents on a
secondary storage medium
Manipulate the database:
Retrieval: Querying, generating reports
Modification: Insertions, deletions and updates to
its content
Accessing the database through Web applications
Share a database allows multiple users and programs
to access the database simultaneously
10. Outline
Database Introduction
An Example
Characteristics of the Database
Actors on the Scene
Advantages of using the DBMS approach
11. An UNIVERSITY example
A UNIVERSITY database for maintaining information
concerning students, courses, and grades in a university
environment
We have:
STUDENT file stores data on each student
COURSE file stores data on each course
SECTION file stores data on each section of each course
GRADE_REPORT file stores the grades that students
receive
PREREQUISITE file stores the prerequisites
13. Database manipulation
Database manipulation involves querying and
updating
Examples of querying are:
Retrieve a transcript
List the prerequisites of the “Database” course
Examples of updating are:
Enter a grade of “A” for “Smith” in “Database”
course
14. Outline
Database Introduction
An Example
Characteristics of the Database
Actors on the Scene
Advantages of using the DBMS approach
15. Database V.S. File
In the database approach, a single repository of data
is maintained that is defined once then accessed by
various users
The major differences between DB and File are:
Self-describing of a DB
Insulation between programs and data
Support of multiple views of the data
Sharing of data and multiuser transaction processing
16. Self-describing nature of a database system
Database system contains not only the database itself
but also a complete definition of the database
structure and constrains
The information stored in the catalog is called Meta-
data (data about data), and it describes the structure
of the primary database.
18. Insulation between programs and data
In file processing, if any changes to the structure of a
file may require changing all programs that access
the file
In database system, the structure of data files is stored
in the DBMS catalog separately from the access
program
This is called program-data independence
19. Support of multiple views of the data
Each user may see a different view of the database,
which describes only the data of interest to that user
It may also contain some virtual data that is derived
from the database files but its not explicitly stored
20. Sharing of data and multi-user
transaction processing
Allowing a set of concurrent users to retrieve from
and to update the database.
Concurrency control within the DBMS guarantees
that each transaction is correctly executed or aborted
For example, when several reservation clerks try to
assign a seat on an airplane flight
(these types of applications are generally called
online transaction processing (OLTP))
21. Outline
Database Introduction
An Example
Characteristics of the Database
Actors on the Scene
Advantages of using the DBMS approach
22. Database Users
Database administrators:
Responsible for authorizing access to the database,
for coordinating and monitoring its use, acquiring
software and hardware resources, controlling its
use and monitoring efficiency of operations.
Database Designers:
Responsible to define the content, the structure, the
constraints, and functions or transactions against
the database. They must communicate with the
end-users and understand their needs.
End Users
System Analysts
23. End Users
Casual: access database occasionally by sophisticated
query language when needed.
(Manager)
Naïve: they make up a large section of the end-user
population. Learn only a few facilities that they may
use repeatedly
(bank clerk)
Sophisticated: These include business analysts,
scientists, engineers, others thoroughly familiar with the
system capabilities.
Stand-alone: maintain personal database by using well
designed GUI (Turbotax users)
24. Outline
Database Introduction
An Example
Characteristics of the Database
Actors on the Scene
Advantages of using the DBMS approach
25. Controlling Redundancy
Controlling Redundancy is one of most important
feature to use DBMS
The traditional file approach, each group independently
keeps their own file.
For example: accounting office keeps data on
registration and billing info; whereas the registration
office keeps track of registration, student courses and
grades.
26. Controlling Redundancy
This redundancy in storing the same data multiple
times leads to several problems:
Logic update – we need to update several times
Storage space is wasted
The file that represent the same data may become
inconsistent
27. Other Advantages of using the
DBMS approach
Restricting unauthorized access to data
Providing Storage Structures (e.g. indexes) for
efficient Query Processing
Providing backup and recovery services
28. Other Advantages of using the
DBMS approach
Providing multiple interfaces to different classes of
users
Representing complex relationships among data
29. When NOT to use DBMS?
The overhead cost of using DBMS:
High initial investment in hardware, software and
training
The cost of defining and processing data
Overhead for security, concurrency control,
recovery, and integrity functions
30. When NOT to use DBMS?
Hence, it may be more desirable to use regular files
under the following situations:
Simple, well-defined database applications that are
not expected to change
Real-time requirements for some programs that
may not be met due to DBMS overheads
No multiple-user access to data
31. Database Administration (DBA)
DBA is a resource that supervises both the database
and the use of the DBMS.
DBA is usually a group, but sometimes it refers to the
database administrator.
33. Policy Formulation and Implementation
Access Privileges
Users should access the database only in ways in
which they are entitled.
Security
Access restrictions ensure that the database is
secure.
Passwords, encryption, and views implement
security.
Effective password protection is critical.
34. Planning for Disaster
Databases can be harmed from hardware and software
malfunctions, and outsides forces like floods and
power outages.
DBA’s must take active role in formulating disaster
recovery plans.
36. Archives
An archive is a place where corporate data is kept.
Information in an archive is removed from the
database and stored in the archive for future
reference.
Archives are usually kept in a mass-storage device
like a disk, tape, CD, or a DVD.
It is important such archives be kept off-site to allow
recovery should disaster strike
37. Data Dictionary Management
Essentially the catalog, but it contains a wider range
of information, including information on tables,
fields, indexes, and programs.
The DBA manages and updates the data dictionary,
which establishes naming conventions for tables,
fields, etc., and data integrity rules.
38. Additional responsibilities of DBA
Training
DBA gives training on the DBMS and how to
access the database
DBMS Support
The DBA is charged with all aspects of a DBMS,
including selection and management
DBA must evaluate each prospective DBMS using
a checklist like that shown in
39. Additional Responsibilities of DBA
Database design
DBA is responsible for tuning the design, i.e.,
making changes that improve system performance.