Databases and Database Users

Database

A database is a collection of related data.

1. Represents an aspect of the real world.
2. Logically coherent collection of data with some inherent
meaning.
3. Designed, built, and populated with data for a specific
purpose.
4. Can be of any size and complexity.
5. May be generated and maintained manually or
computerized.

Implicit properties of a database

Database Management System (DBMS)

A computerized system that enables users to create
and maintain a database.

Database Management System (DBMS)

A general-purpose software system that facilitates
the process of defining, constructing, manipulating,
and sharing databases.

1. Defining a database.
2. Constructing a database.
3. Manipulating a database.
4. Protecting a database.
5. Maintaining a database.

Functions of a DBMS

Defining a database

Specifying data types, structures, and constraints of data to be stored in the database.

Constructing a database

Process of storing the data on a storage medium
which is controlled by the DBMS.

Manipulating a database

Fetching or querying the database to retrieve
specific data, updating database information to
reflect changes and generate reports.

Protecting a database

System protection against hardware or software
malfunction or crashes, and security protection
against unauthorized and malicious access.

Maintaining a database

Allowing the database system to evolve as
requirements change over time.

1. Self describing nature.
2. Insulation between programs, data, and data
abstraction
3. Support for multiple views of data
4. Sharing data and multi use transaction
processing.

Characteristics of the Database Approach

Self describing nature

Complete definition or description of the database
structure and constraints.

Insulation between programs, data, and data
abstraction

Structure of data files is stored in the DBMS catalogs
separately from the access programs.

Insulation between programs, data, and data
abstraction

Implementation of the operation is specified
separately and can be changed without affecting
the interface.

Support for Multiple Views of data

A multi user DBMS has a variety of distinct
applications. Provides facilities for multiple views.

View

A subset of data that may contain virtual data that
is derived from the database but not explicitly
stored.

Sharing data and multiuser transaction processing

Allows multiple users to access the database at the
same time.

Sharing data and multiuser transaction processing

Concurrency control to ensure that several users
trying to update the same data are correct.

● Database Administrators
● Database Designers
● End Users
● System Analysts
● Application Programmers

Actors on the scene

Database Administrators

● Responsible for authorizing access to the
database, coordinating, and monitoring the use
and acquisition of software and hardware
resources.
● Accountable for problems such as security
breaches and poor system response time.

Database Designers

Identifies the data to be stored in the database.
Chooses the appropriate structures to represent and
store data.

End Users

● People whose jobs require access to the database
for querying, updating, and generating reports.
● Casual End Users, Naïve or Parametric End Users,
Sophisticated End Users, Standalone Users

Casual End Users

Occasional access to the database. Uses a
sophisticated database query interface to specify
request and are typically middle or high level
managers.

Naïve or Parametric End Users

Revolves around constantly querying and updating
the database, using standard types of queries and
updates.

Sophisticated End Users

Engineers, scientists, business analysts, and others
who thoroughly familiarize themselves with the
facilities of the DBMS.

Standalone Users

Maintains personal databases by using ready-made
program packages that uses menu-based or
graphic-based interfaces.

System Analysts

Determines the requirements of end users,
especially the naïve and parametric end users and
develops specifications for standard transactions
that cater to the requirements.

Application Programmers

Implements the specifications as programs; then
test, debug, documents, and maintain the
transactions in the database.

Workers behind the scene

● DBMS System Designers and Implementers
● Tool Developers
● Operators and Maintenance Personnel

DBMS System Designers and Implementers

Design and implement the DBMS modules and
interfaces as software packages.

Tool Developers

Design and implement tools. Tools that facilitate
database modeling, design and performance
improvement of the DBMS.

Operators and Maintenance Personnel

Actual running and maintenance of hardware and
software environment of the DBMS.

1. Controlling redundancy
2. Restricting unauthorized access
3. Provide persistent storage for program objects
4. Implement storage structures
5. Efficient search techniques in query processing.
6. Backup and recovery
7. Multiple user interfaces
8. Representation of complex relationship among
data
9. Enforce integrity constraints
10. Permit inferencing and actions using checks and
triggers
11. Potential for enforcing standards
12. Reduced application development time
13. Flexibility
14. Availability of up-to-date information
15. Economies of scale

Advantages of using DBMS Approach

1. Simple, well-defined database application that are not
expected to change at all.
2. Stringent, real-time requirement for some applications that
may not be met due to DBMS overhead.
3. Embedded systems with limited storage capacity.
4. No multiple-user access to data.

When not to use a DBMS