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Introduction
 An
organization's survival relies on
decisions made by management
 To make decisions, managers rely on good,
timely, and relevant information.
 Information is obtained by ===
 As data are the building blocks of
information, quality of data is critical to
quality of information, decision-making,
and organizational well being.
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Data and Information
•
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Data
Raw Facts, without any meaning
Managed by DBMS
Information
Has meaning, created by
processing data.
Combined with rules, produces
knowledge
Created and Reported by
Management Information
System.
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Database
a database is a structured collection of
data and metadata that enable computer
programs to find answers to queries
 Data retrieved in answer to these queries
assume the form of information useful for
decision making
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Qualification for Database

Most professionals consider collection of
data as database only if it:
 is
managed to ensure its integrity and quality
 allows shared access by a community of users
 has a schema
 supports a query language.
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DBMS
Complex set of software program that controls
the organization, storage, management, and
retrieval of data from a database
 Accepts requests for data from application
program and instructs operating system to
transfer the appropriate data
 Enables addition of new categories of data to
the database without disruption to the existing
system

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Components of DBMS
Modeling language to define schema of
each database hosted according to the
data model
 Data structures optimized to deal with
huge data stored on a permanent data
storage device
 Query language and report writer
 Transaction mechanism to ensure data
integrity

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Importance of DBMS
Facilitates effective & efficient data
management
 Facilitates information retrieval with ad
hoc queries
 Facilitates access to large, organized data
 Promotes integrated view of an
organization’s operations
 Reduces chance of data inconsistency

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Functions of DBMS

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Manages data dictionary
Manages data storage
Responsible for data transformation &
presentation
Manages data integrity & security
Controls multi-user access
Manages backup & recovery
Manages database language & API
Manages database communication interface
Manages video
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Evolution
Databases were first created to perform
clerical tasks
 Later, they were designed for requesting
information
 These needs were met through File
Systems

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File Systems
File systems may be considered as less
powerful database technology
 Data organized according to expected use
 Manual files systems were computerized
by data Processing specialists

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File System Terminology
Field - Group of characters with specific
meaning
 Record - Logically connected fields
describing a person, place, or thing
 File - Collection of related records

 E.g.
Telephone Directory
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Problems with File System
Extensive use of 3GL
 No support for ad hoc query
 Results in islands of Information
 Changing data characteristic requires
modifying data access programs (data
dependence)
 Changing file structure requires modifying
related programs (structural dependence)

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Problems with File System (Contd)

No standard for field nomenclature

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Data Redundancy
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E.g. SSN, Socnum, Empid)
Conflicting versions of same data
Results of uncontrolled data redundancy
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Data anomalies
Data inconsistency
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Database Systems
Logically related data stored in a single
repository
 Elimination of inconsistency, data
anomalies, data dependence, & structural
dependence
 Storage of data structures, relationships,
and access paths

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Database vs. File Systems
Figure 1.6
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Database System Environment
Figure 1.7
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Types of Database Systems

Single-user vs. multiple-user database
 Desktop,
Workgroup, Enterprise
Central vs. Distributed use
 Productional vs. Transactional
 Decision Support vs. Data Warehouse

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