2. Database Management System
• Database Management System is a collection of
interrelated data and a set of programs to access
those data.
• Primary Goal of DBMS- provide a way to store and
retrieve database.
• Management of data involves both defining structure
for storage of information and proving mechanisms
for the manipulation of information.
4. File System
• File processing system is supported by a
conventional operating system.
• This System stores permanent records in
various files and it needs different application
programs to extract and Add records.
• Keeping Organizational information in a file-
processing system has number of major
disadvantages.
5. Disadvantages of File System
• Data Redundancy and Inconsistency
• Difficulty in accessing data
• Data isolation
• Integrity problems
• Security problems
7. Data Abstraction
• For the system to be usable ,it must retrieve
data efficiency.
• The need for efficiency has led designers to
use complex data structures to represent data
in the database.
• Since many database system users are not
computer trained, developers hide the
complexity from users through several levels
of abstractions.
8. Levels of Abstraction
1. Physical Level : The lowest level of
abstraction describes how the data are
actually stored.
2. Logical Level : The next – higher level of
abstraction describes what data to be stored
in database.
3. View Level : The highest level of abstraction
describes only a part of the entire database.
9. Instances and Schemas
• Database changes over time as information is
inserted and deleted. The Collection of information
stored in the database at a particular moment is
called Instance of database .
• The overall design of the database is called the
database Schema .Schemas are changed
infrequently.
10. • Database system have several schemas
partitioned according to the levels of
abstraction.
• Physical schema describes the database
design at physical level
• Logical schema describes the database design
at the logical level.
• Database may have several schemas at view
level, sometimes called Subschemas, that
describes different views of database.
11. Data Models
• Structure of Database is the Data Model.
• A Collection of Conceptual tools for describing Data, Data
Relationships, Data Semantics and consistency constraints.
The Concept of Data Model has 2 sections
1.The Entity Relationship Model
2.The Relational Model
12. The Entity Relationship Model
• The Entity Relationship Model ( E.R Model ) is based on the
perception of a real world that consists of a collection of
basic objects called Entities.
• An Entity is a thing or Object in the real world what is
distinguishable from other objects.
• For example each person is an Entity and bank Accounts
can be considered as Entities.
• Entities are described in the database by set of attributes.
13. • A relationship is an association among several
Entities. Eg:
Rectangle which represent Entity Sets.
Eclipses which represent Attributes.
Diamonds which represent Relationship among
Entity sets.
Lines which link attributes to Entity Sets and Entity
Sets relationships
14. Relational Model
• The Relational Model uses a collection of tables to
represent both data and the relationships among those
data.
• Each table has Multiple Columns, Each Columns has a
Unique name.
• The Relational Model is an Example or Record Based
Model.
• Record Based Model is the database structured in fixed
formats records of several types.
15. • Each table contains records of a particular type each
record type defines a fixed number of files or
attributes.
• The Relational model is at the lower level of
Abstraction than the ER Model and then translated
to the Relational Model
16. Other Data Model
• The Object Oriented Data Model is another data
model that has seen increasing attention.
• The Object Oriented Model can be seen as
Extending of the ER Model with notions of
Encapsulation, Methods and Object identity.
• The Object relational Data Model combines features
of the Object Oriented Data Model and Relational
Data Model.
17. Data Base Language
• A Database system provides a data definition
language to specify the database schedule and a
data Manipulation languages to Express database
queries and updates.
Data Definition Language
• A Database schema by set of definitions Expressed
by a special language called Data Definition
Language.
18. Data Manipulation Language
• Retrieval of Information stored in Database.
• Insertion of New Information in Database.
• Decision of Information from Database.
• Modification of Information stored in Database.
• Enables User to access or Manipulate data as organized
by Appropriate Data Model.
19. Procedural Dml
• Requires user to specify what data and how to get
data.
Declarative Dml
• Requires user to specify what data are needed
without specifying how to get the data.
20. Database Access for Application
Programs
• Application programs used to interact with database
application programs written in C,C++,Cobol or Java.
• By Providing an application programs can be used to send
DML and DDL statements.
• By Extending the Host Language syntax to embed DML calls
21. Database Users and User Interfaces
• There are 4 different types of databases system users :
• Navie Users are unsophisticated users who interact with the system
invoking one of the application programs that have been written previously.
• Application programmers are computer professionals who write
application programs
• Sophisticated users interact with the systems without writing programs.
• Specialized users are sophisticated users who write the specialized
database applications that do not fit into the traditional data processing
framework.
22. Database Administrator
• Main reason fro using DBMS is to have central control of both the
data an the programs that access those data.
• Functions of DBA
• Schema Definition
• Storage Structure and Access method Definition
• Schema and physical organization Modification
• Routine Maintenance
