The
characteristics of database approach are
1.
Self-describing nature of a
database system
2.
Insulation between programs and
data, and data abstraction
3.
Support of multiple views of
the data
4.
Sharing of data and multi-user
transaction processing
1. Self-Describing
Nature of a Database System
A
fundamental characteristic of the database approach is that the database system
contains not only the database itself but also a complete definition or
description of the database structure and constraints. This definition is stored in the DBMS catalog,
which contain information such as the structure of each file, the type and
storage format of each data item, and various constraints on the data. The information
stored in the catalog is called meta-data, and it describes the
structure of the primary database
2. Insulation
between Programs and Data, and Data Abstraction
In
traditional file processing, the structure of data files is embedded in the
application programs, so any changes to the structure of a file may require changing
all programs that access this file. By contrast, DBMS access programs do
not require such changes in most cases. The structure of data files is stored
in the DBMS catalog separately from the access programs. We call this property program-data
independence.
In
DBMS environment we just need to change the description of STUDENT record in
catalog to reflect add new data item Date of Birth.
In
object oriented database management System we write operational methods, where
the user can get the functionality without knowing the implementation code this
property is called as Operational Independence.
Data
Abstraction in DBMS is support for program –data independence, Operational
Independence.
Data
Abstraction: The characteristic that
allows program data independence and program operation independence is called
data abstraction. DBMS provides essential information to a user by hiding the
internal details
3.
Support of Multiple Views of the Data
A
database typically has many users, each of whom may require a different
perspective or view of the database. A
view may be a subset of the database
or it may contain virtual data that is derived from the database files
but is not explicitly stored. Some users may not need to be aware of whether
the data they refer to is stored or derived. A multiuser DBMS whose users have
a variety of distinct applications must provide facilities for defining
multiple views. For example, student wants to get his exam results, so his
number, marks are given as student view which satisfy his need.
4.
Sharing of Data and Multiuser Transaction Processing
A
multiuser DBMS must allow multiple users to access the database at the same
time. This is essential if data for multiple applications is to be integrated
and maintained in a single database. The DBMS must include concurrency control software to ensure that several users trying to
update the same data do so in a controlled manner so that the result of the
updates is correct.
For example, when several reservation clerks
try to assign a seat on an airline flight, the DBMS should ensure that each
seat can be accessed by only one clerk at a time for assignment to a passenger.
These types of applications are generally called online transaction processing
(OLTP) applications.
