2. Database :-
A Database is a structure that can store information
about multiple types of entities ,and the relationships
among the entities .
Entity :-
An entity is a person , place, object or idea for which
you want to store and process data.
Attribute:-
An Attribute is a characteristic or property of an entity.
The term used in this text exactly as it is used.
Data Base Management System :-
A DBMS is a program or a collection
of programs , though which users interact with a database . The actual
manipulation of the underlying in handled by the DBMS .
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3. Database application:-
An application program (or set of related
programs)that is used to perform a series of database activities (Create, read,
update and delete) on behalf of database users. Each database application
performs some combination of the following basic operation
1)Create :- Add new data to the database.
2)Read :- Read current database data (often presented in a useful format on a
computer screen or on a printed report).
3)Update :- Update or modify current data.
4)Delete :- Delete current data from the database.
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4. DBMS Advantages
DBMS has many advantages such as:
Reduction in data Redundancy :-
It means that DBMS helps in removing duplicate
data from the database. It will notice that Redundancy leads to several problems:
i) Duplication of Efforts .
ii) Save the storage space /memory where data is saved.
Provides Security :-
Restrict users to access all the information of the database by
providing passwords and rights .there are also various coding techniques to maintain the security of
important and crucial information from unauthorized users and accidents.
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5. DBMS Advantages
Data can be shared among various users:-
In a database system , data can be
easily shared by different users .For example ,student data can shared by teacher
department subject wise ,Fee department ,library etc.
Data Integrity :-
since a large number of users can access database together at the same
time . So, to maintain the same data/information correct every time and at every
place during any operation is called data integrity.
Maintenance of data integrity :-
data Integration can be understood by the fact
that data contained in the database should be accurate and consistent.
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6. Types of DBMS Models
These categories are made on the basis of the ways in which data are stored in
the database :
1)Flat file or sequential .
2)Hierarchical
3)Network
4)Relational
5)Entity–relationship model
6)Object database
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7. Sequential or Flat File
Flat File:-
A Flat File can be defined as a text file in which you can organize the data in
your own format and it is not linked with any other file .In this the data is processed in the
way the data is stored.
Example:-MS Spread Sheet.
Item name Price Quantity Store Name Date of sale
Bread 15 5 saravana 30-08-2014
Butter 46 6 saravana 30-08-2014
Biscuits 56 8 saravana 01-09-2014
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8. Sequential or Flat File
Advantages of Flat File System:-
1) It is simple and easy to implement.
2) It can be used for small database
3) It is used where no links between data or files are required.
Disadvantage of File System :-
1)Duplication of data Entries.
2)Since the access mode is sequential or in a single order, the system gets
slower for large database.
3)The file is hard to recover if it is corrupted or system crashes .
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9. Hierarchical Database Model
• In this kind of database, data are stored in the form of a hierarchy .Hierarchy
database is like a tree structure which has one root and many branches .It uses the
concept of parent child relation ship .in this type of database a single file may have
many relationship.
this system is very advance compare to sequential system(a flat file).
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11. Hierarchical Database Model
Advantages of Hierarchical databases :-
it is having following advantage
1) Hierarchical model is simple to construct.
2)This type of database is generally used in daily life organizations
where data is organized in hierarchically organized domains,
component assemblies in manufacturing ,personnel organization in
companies.
3)Accessing of data is faster in hierarchical database compared to
sequential database.
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12. Hierarchical Database Model
Disadvantages of Hierarchical Database :-
1) Complex implementation
2)Difficult to manage
3)Lacks structural independence
4)Complex applications programming and use
5)Implementation limitations
6)Lack of standards
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13. Network database model
• In this model, a parent can have many children and a child can also
have many parent records. These records are physically linked
through linked lists.
network model was developed in mid 1960s as part of work of
CODASYL(Conference on Data Systems Languages) which
proposed programming language COBOL(1966) and then network
model(1971).
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15. Network database model
Advantages of network Model:-
1)It eliminates unnecessary duplication of data with associated errors and
costs.
2)It uses concept of a data definition language ,data manipulation language .
3)It uses concept of m:n linkages or relationships, which mean that an owner
record can have many members records. Similarly a member record can have
several owners .but a hierarchical model allows only 1:n
Disadvantages of network Model :-
1)System complexity
2)Lack of structural independence
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16. Relational data model :-
In this model of DBMS ,data is stored in two- dimensional table (rows, and columns ),this is a
model relation between two tables exists with something in common or some data which these
two tables share. Each column of a table is referred ta as an attribute and the values which it may
contain is called domain of values.
In this model was proposed by IBM researcher E.F.Codd in 1970. it is more of a concept than a
data structure varies substantially from one RDBMS to another .Relational database model use
relational concept of mathematics in a table .
You can understand Relational Model where
Each row is a record or tuple.
Each column is an attribute.
Primary Key:-
the Primary Key of a table uniquely identifies the record .
Foreign Key :-
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The Foreign key is the key of a table which is used for referencing the other table .
17. Relational data model :-
• Example :1 Student table and its primary Key
ID No
(Primary Key)
Student Name Class Department
S34877 Raja Sekhar MLIS Library and Information Science
S34878 Avani MSc Computer Science
S34879 Kadiresan MLIS Library and information science
S34880 Amees MLIS Library and information science
S34881 Gopi MA English
S34882 Shyndeep MLIS Library and information science
S34883 Rajesh MBA Business Management
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18. Relational data model :-
• Example :- Library Table
Book No
(Primary Key)
ID No
(Foreign Key)
Title Issued Date
12567 S34877 Colon classification 26/09/2014
15498 S34878 Database System 16/09/2014
12578 S34879 Information Resources 22/092014
12576 S34880 MARC21 14/092014
14582 S34881 William Shakespeare 24/09/2014
12565 S34882 Library Associations 22/09/2014
14825 S34883 Business Law 15/09/2014
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19. Relational data model :-
Advantages of Relational data Model:-
1)Structural independence.
2)Improved conceptual simplicity.
3)Easier database design, implementation, management, and use.
4)Ad hoc query capability.
5)Powerful database management system.
Advantages of Relational data Model:-
1)Substantial hardware and system software overhead.
2)Can facilitate poor design and implementation
3)May promote “islands of information "problems
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20. Entity Relationship Models
Entity- relationship model is a logical representation of data for
an organization or for a business area .the E-R model consists of entities
which have attributes and relationships between these entities .
E-R model was proposed by peter in 1976. simply stated ,the
ER model is a conceptual data model that views the real world as entities
and relationships.
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22. Entity Relationship Models
Advantages of Entity Relationship Models:-
1)Exceptional conceptual simplicity
2)Visual representation
3)Effective communication tool
4)Integrated with the relational data model.
Disadvantages of Entity Relationship Models:-
1)Limited constraint representation
2)Limited relationship representation
3)No data manipulation language
4)Loss of information content
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23. Object Oriented Model
An object database (also object-oriented database
management system) is a database management system in which
information is represented in the form of objects as used in object-oriented
programming. Object databases are different from relational
databases which are table-oriented.
•Object is described by its factual content
•Includes information about relationships between facts within object and
relationships with other objects.
•Subsequent OODM development allowed an object to also contain
operations
••Object becomes basic building block for autonomous structures
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24. Object Oriented Model
Basic structure of OODB model:-
Object: abstraction of a real-world entity.
Attributes describe the properties of an object.
Objects that share similar characteristics are grouped in classes.
Classes are organized in a class hierarchy.
Inheritance is the ability of an object within the class hierarchy to
inherit the attributes and methods of classes above it.
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26. Object Oriented Model
Advantages of OODBMS model:-
1)Object model intuitively closer to real world
2)Extensibility – inheritance
3)Complex values
4)Removal of impedance mismatch
5)More expressive query language
6)Tight coupling between data and applications allows schema
to capture more of the meaning of applications
7) Support for long transactions
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27. Object Oriented Model
Advantages of OODBMS model:-
8) Better support for applications like software engineering or
computer aided design (CAD)
9) Arguably better performance, though benchmarks have mainly
been applied in areas like engineering support to which OODBMS
are better suited.
Disadvantages of OODBMS model:-
1) Lack of a theoretical foundation, so exact meaning of OODM
is not well defined (though this is mitigated by the ODMG model)
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28. Object Oriented Model
Disadvantages of OODBMS model:-
2)More difficult to get staff experienced with OODBMSs
3)Lack of standards (mitigated by ODMG's OQL)
4)Competition from relational and object-relational DBMS's
5)Encapsulation compromised to optimize queries (but in RDBMS's,
normalization may be compromised to improve performance).
6) OODBMS's usually control concurrency by locking; locking
an inheritance hierarchy is difficult and may affect performance.
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29. Object Oriented Model
7) OODM is inherently more complex than relational data model;
OODBMS provides more complex functionality than RDBMS;
complexity leads to higher implementation and maintenance costs.
8) Lack of views; but are views necessary with an object model?
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