DBMS PPT.pptx

Submitted To: Submitted By:
Aishwarya Anand Avinash Choudhary
Database
Management System

Conte
nt
 What is Database Management System?
 Why Use a DBMS?
 Purpose of DBMS
 levels or layers of DBMS
 Components of DBMS
 Advantage of DBMS
 Disadvantage of DBMS
 DBMS Languages

What is Database Management
System?
A Database Management System (DBMS), or simply a Database
System (DBS) consist of :
 A collection of interrelated and persistent data (usually referred
to as the database (DB)).
 A set of application programs used to access, update and
manage that data (which form the data management system
(MS)).

Why Use a DBMS?
 Data independence and efficient access.
 Reduced application development time.
 Data integrity and security.
 Uniform data administration.
 Concurrent access, recovery from crashes.

Purpose of DBMS
1. Data redundancy and inconsistency
 Same information may be duplicated in several places.
 All copies may not be updated properly.
2. Difficulty in new program to carry out each new task
3. Data isolation —
 Data in different formats.
 Difficult to write new application programs.
 files and formats

Purpose of DBMS …
Security problems
 Difficult to enforce this with application programs.
 Data restrictions
Integrity problems
 Data may be required to satisfy constraints.
 Again, difficult to enforce or to change constraints with the
file-processing approach.

levels or layers of DBMS
 External Level: - External Level is described by a schema i.e.
it consists of definition of logical records and relationship in
the external view.
 Conceptual Level: - Conceptual Level represents the entire
database. Conceptual schema describes the records and
relationship included in the Conceptual view.
 Internal Level: - Internal level indicates hoe the data will be
stored and described the data structures and access method to
be used by the database.

Components of DBMS
1. Hardware
2. Software
3. Data
4. People
5. Procedure

Advantage of DBMS
 Controlling Redundancy
 Sharing of Data
 Data Consistency
 Integration of Data
 Integration Constraints
 Data Security
 Report Writers
 Control Over Concurrency
 Backup and Recovery Procedures
 Data Independence

Disadvantage of DBMS
 Cost of Hardware and Software
 Cost of Data Conversion
 Cost of Staff Training
 Appointing Technical Staff
 Database Damage

DBMS Languages
Data Definition Language-DDL
 Data Definition Language (DDL) statements are used to
define the database structure or schema.
Some examples:
 CREATE - to create objects in the database
 ALTER - alters the structure of the database
 DROP - delete objects from the database
 TRUNCATE - remove all records from a table, including all
spaces allocated for the records are removed
 COMMENT - add comments to the data dictionary
 RENAME - rename an object

Data Manipulation Language
(DML)
Data Manipulation Language (DML) statements are used for
managing data within schema objects.
Some examples:
 SELECT - Retrieve data from the a database
 INSERT - Insert data into a table
 UPDATE - Updates existing data within a table
 DELETE - deletes all records from a table, the space for the
records remain
 MERGE - UPSERT operation (insert or update)
 CALL - Call a PL/SQL or Java subprogram
 EXPLAIN PLAN - explain access path to data
 LOCK TABLE - control concurrency

DBMS PPT.pptx

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