DBMS - QUICK GUIDE
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DBMS - OVERVIEW
Database is a collection of related data and data is a collection of facts and figures that can be
processed to produce information.
Mostly data represents recordable facts. Data aids in producing information, which is based on
facts. For example, if we have data about marks obtained by all students, we can then conclude
about toppers and average marks.
A database management system stores data in such a way that it becomes easier to retrieve,
manipulate, and produce information.
Traditionally, data was organized in file formats. DBMS was a new concept then, and all the
research was done to make it overcome the deficiencies in traditional style of data management.
A modern DBMS has the following characteristics −
Real-world entity − A modern DBMS is more realistic and uses real-world entities to design
its architecture. It uses the behavior and attributes too. For example, a school database may
use students as an entity and their age as an attribute.
Relation-based tables − DBMS allows entities and relations among them to form tables. A
user can understand the architecture of a database just by looking at the table names.
Isolation of data and application − A database system is entirely different than its data. A
database is an active entity, whereas data is said to be passive, on which the database works
and organizes. DBMS also stores metadata, which is data about data, to ease its own process.
Less redundancy − DBMS follows the rules of normalization, which splits a relation when
any of its attributes is having redundancy in values. Normalization is a mathematically rich
and scientific process that reduces data redundancy.
Consistency − Consistency is a state where every relation in a database remains consistent.
There exist methods and techniques, which can detect attempt of leaving database in
inconsistent state. A DBMS can provide greater consistency as compared to earlier forms of
data storing applications like file-processing systems.
Query Language − DBMS is equipped with query language, which makes it more efficient to
retrieve and manipulate data. A user can apply as many and as different filtering options as
required to retrieve a set of data. Traditionally it was not possible where file-processing
system was used.
ACID Properties − DBMS follows the concepts of Atomicity, Consistency, Isolation, and
Durability normallyshortenedasACID. These concepts are applied on transactions, which
manipulate data in a database. ACID properties help the database stay healthy in multitransactional environments and in case of failure.
Multiuser and Concurrent Access − DBMS supports multi-user environment and allows
them to access and manipulate data in parallel. Though there are restrictions on
transactions when users attempt to handle the same data item, but users are always
unaware of them.
Multiple views − DBMS offers multiple views for different users. A user who is in the Sales
department will have a different view of database than a person working in the Production
department. This feature enables the users to have a concentrate view of the database
according to their requirements.
Security − Features like multiple views offer security to some extent where users are unable
to access data of other users and departments. DBMS offers methods to impose constraints
while entering data into the database and retrieving the same at a later stage. DBMS offers