Information Technology and Systems
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Chapter 8 : Database Management
Database System
Data Hierarchy
Components of a Database System
File Organization
Data Models
Record-Based Logical Models (RBLMs)
Object-Based Logical Models (OBLMs)
Physical Data Models
Database Management Approach
Characteristics of a Well-designed Database System
Types of Databases
Database Development
Managing Data
Benefits and Limitations of DBMS
Data Views
The Entity-Relationship Model
Basic Elements in the E-R Model
Converting an E-R Model to a Relational Model
E-R Structures
Importance of the E-R Model
The Relational Database Model
Structured Query Language
Designing a Relational Database
Data Dictionary
Data Warehousing
Data Mining
Distributed Databases
Object-Oriented Databases
Object Relational Database System
Chapter Summary
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A database management system is a collection of interrelated data and a set
of programs for accessing that data. Data is logically organized into
characters, fields, records, files, and databases in an information system.
The five main components of a database system are data, hardware, software,
procedure, and user. File organization is defined as the logical sequence in
which the records are organized in the file. File organization can be of the
following types: pile, indexed, sequential, indexed-sequential, and hashed.
Data models are mainly used for specifying the overall logical structure of
a database and for providing a higher-level description of the
implementation. Data models fall into three different categories, namely,
record-based logical models, object-based logical models, and physical data
models.
The DBMS is software that allows the programmer and administrators to
create, delete, store, retrieve, organize, interrogate, and maintain
databases for providing the required information to the end users and their
organizations. |
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An ideal database system should ensure efficiency in storage and retrieval of
data, data integrity, data independence, data consistency, along with data
sharing and security. In an organization, there are various categories of
databases based on their use. They include operational databases, analytical
databases, hypermedia databases, data warehouses, and distributed databases.
The process of database development is divided into the three phases,
namely, database planning and modeling; database design; and database
implementation and maintenance.
The Entity-Relationship model (E-R) is based on the perception of a real
world that consists of entities and the inter-relationships between these
entities. The model was proposed as a basis for unifying the different views
of data, which included the network and the relational views. The basic
elements of this model include entities, relationships, and attributes. The
E-R model should be converted to a relational model for it to be directly
used in a database. The model has been extended to and is being widely used
in the field of database designing.
A Relational Database Management System stores data in the form of tables
and then links or relates those tables to provide answers to the diverse
queries of users. A relational database system can generate reports for the
queries made. Structured Query Language (SQL) is a popular query language.
To write a SQL query, a user needs to use keywords like SELECT, FROM, WHERE,
followed by attributes like name, address, etc.
Data dictionaries contain details of all the files in the database, the
records in each file, and the details of the fields in each record. Data
dictionaries enforce standard data element definitions whenever end users
and application programs use a DBMS to access an organization's databases.
According to Bill Inmon, “A warehouse is a subject-oriented, integrated,
time-variant and non-volatile collection of data in support of management's
decision making process.” Data warehouse architecture represents the overall
structure of data and has three components, namely, data source, data
loaders and DBMS, and query and analysis tools.
Data mining refers to extracting and analyzing the data from different
sources and summarizing it into useful information. The main objective of
data mining is to look for (hidden) patterns in the data that can be used
for formulating a business strategy or to look for unusual behavior.
A distributed database is a single logical database consisting of two or
more data files which are placed at various sites on a computer network. All
the distributed databases are controlled by a centralized distributed
database management system (DDBMS).
An object-oriented database (also referred to as an object-oriented database
management system or OODBMS) is a set of objects. The state, behavior, and
relationships of these objects are characterized in line with the
object-oriented data model. In other words, in these databases, the data is
modeled and created as objects.
The relational databases had certain shortcomings. As a way out for
overcoming these limitations of the relational databases, the concept of
Object Relational Database Management System (ORDBMS) was introduced. The
ORDBMS allows the software developers to incorporate their customized data
types and methods into the database. These databases support both object and
relational models and thus enable the reusability of the structure.
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Short Case Studies / Caselets