Object oriented database (OODB):-

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• Object oriented database (OODB)-
• Object oriented database (OODB) are dependent
  on the object oriented programming paradigm. It
  enable us to create classes, organize object,
  structure an inheritance hierarchy and call
  methods of other classes. Beside these it also
  provides the facilities associated with standard
  database systems. However object oriented
  database system have not yet replaced the RDBMS
  in commercial business applications.
• Although a relational database can be used
  to store and manage object, it does not
  understand objects as such. Therefore, a middle
  layer called object manager or object-oriented
  layer software is required to translate object
  into tuples of a relation.

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• Different approaches for designing an object
  oriented database
• Designed to store, retrieve and manage objects
  created by programs written in some object
  oriented languages (OOL) such as C or Java.
• Designed to provide object oriented facilities to
  user of non object-oriented programming languages
  (OOPLs) such as C or Pascal
• The user will create classes, objects,
  inheritance hierarchy, and so on and the database
  system will store and manage these objects and
  classes. This second approach, thus turns
  non-OOPLs into OOPLs. A translation layer is
  required to map the object created by user into
  objects of the database system

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• Storing and Accessing objects-
• The data part of all objects of a class are
  stored individually in a database. The program
  part of the class are stored as part of the
  database schema along with the type definitions
  of the classes
  Objects can also be given names
  to allow their access. However, such an approach
  will not work hen the number of objects in a
  database are large in numbers say in the range of
  millions. Another method is to collect object
  into a group. a group is given a name. The
  programs will then iterate over a group to find
  out the required object.
• A special case of a collection is the
  class-extent. A class-extent is the objects
  belonging is the collection of all the objects
  belonging to a class. Whenever a new object needs
  to inserted be inserted into a class it is
  inserted into its class-extent automatically.
  Similarly, whenever a new object need to be
  deleted, it is deleted from the respective class
  extent.

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• A sample object oriented database-
• A sample object oriented is shown in figure
• The solid lines(-) in the figure represents
  class-subclass link. The dash(---) represents
  attribute domain link. The class vehicle is the
  root of a class composition hierarchy that
  involves vehicle specs and company. The class
  vehicle is also the root of a class hierarchy
  that involves the subclasses two wheeler and four
  wheeler. The class company is in turn the root of
  a class hierarchy that involves the subclasses
  Domestic company and foreign company. It is also
  the root of a class composition hierarchy that
  involve the class employees

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Object Oriented Database (OODB)-
Vehicle specs
Vehicle
Length Width Height Type Fuel
Code Color Specifications Manufacturer
Employee
Four Wheeler
Company
Two Wheeler
Gear Seating type No_ of_ doors
Company _name President Place
Emp _Code Emp_ Name Age
Gear Seating type
Foreign Company
Domestic company
Dom _Com_ name Dom_ president Dom Place
For _Com_ name For_ president For Place
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• Advantages of OODBMS over RDBMS-
• RDBMS does not allow nested structure. nested
  structure applications are found in CAD/CAE,
  aerospace science, etc. It is easier to navigate
  through these complex structures in the firm of
  objects rather than in the from of table and
  records.
• Relational database have only a limited number of
  data type like integer, char, text, etc. although
  we can create complex data types in relational
  database by combining fields, these are
  restricted by their base data type and sub
  classing with inheritance.
• Object oriented database are favored in those
  application where the relationship among data
  elements are more important than data items
  themselves. However, relational database are used
  in those applications where the values of data
  elements are more important. If a record makes
  sense only when used in context of other records,
  then an object oriented database would be more
  appropriate.

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• Distributed DBMS(DDBMS)-
• Some organization use distributed database system
  rather than a centralized database. In the
  centralized database system data resides in one
  single location. But in a distributed database
  system, database is stored in several computers.
  The computers in a distributed system
  communication and exchange data among one other
  using leased lines, telephone lines or other
  means of communication. These computers do not
  share memory or clock. Each of the computers in a
  distributed system. Participates in the execution
  of transactions. These computer can also be known
  as sites or nodes.

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• Advantages of distributed database-
• Data sharing since data is distributed on
  multiple computers, user operating on one
  computer can work on data available on any
  another computer.
• Distributed control- unlike centralizes database
  system, where a single database administrator
  controls the database, in a distributed system
  responsibility of control is divided among local
  administrators for each computer thus local
  administrators have a certain degree of control
  over the database stored locally.
• Reliability and Availability- Even if one site
  fails in the distributed system the remaining
  site can continue working. If data is replicated
  among multiple computers, failure of any one
  computer does not case shutdown of the entire
  database system
• Faster Query processing- Queries involving data
  at several sites can be split into sub queries
  can then be executed in parallel by several
  sites, such a parallel computation allows faster
  processing.

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• Disadvantages of distributes database-
• Increase cost- it is more difficult to develop
  software packages to implement distributed
  database system. Also cost involved in physically
  linking different sites
• More Error prone-since the sites that comprise
  distributed database system operate in parallel,
  it is very difficult to ensure the correctness of
  data. The algorithms are more error prone and
  have greater potential for bugs,
• Increased overhead- maintaining physical links
  between the sites and exchanging messages among
  computer is an additional overhead associated
  with distributed systems that are absent in the
  case of centralized system

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• Advantages of DBMS-
• It represents complex relationships among
  different data items.
• Keeps tight control on data redundancy.
• Enforces user defined rules to ensure the
  integrity of data in a table from.
• Maintains data dictionary for the storage of
  information pertaining to data fields and data
  manipulation.
• Ensure that data can be shared across all
  applications.
• Enforces data access authorization
• Has an automatic intelligent backup and recovery
  procedure of data.
• Has different interfaces through which user can
  manipulated data.

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Object Oriented database- Different Flavors of
ORACLE available Relational- The traditional
ORACLE relation Database (RDBMS). Object-relation
al- The traditional ORACLE relational
database, Extended to include Object-oriented
concepts and structures such as abstract data
type, nested tables, and varying
arrays Familiarity with the function and
features of the core Oracle relational
database Object-oriented- An object-oriented
database whose design in based solely on
Object-Oriented Analysis and Design
principles OO capabilities are used the
functions and data types available in oracle as
well as its programming languages( SQL and
Pl/SQL).
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• Why should objects be used-
• Object reduce complexity by giving an intuitive
  way of representing complex data and its
  relations.
• Besides simplifying the interaction with data,
  object may help in other ways.
• OO features are-
• Object reuse
• Standards adherence
• Object types-
• Abstract Data type- abstract data types is a
  data type that consists of one or more subtypes
• Example- address
• Street Vrachar2(50)
• City Varchar2(25)
• State Varchar2(25)
• Zip Number

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• Naming conventions for objects-
• When working with OO the following rules should
  be enforced
• Table and column name will be Singular(such as
  EMPLOYEES, Name, and State)
• Abstract data type name will be singular nouns
  with a _TY suffix (such as PERSON_TY or
  ADDRESS_TY)
• Table and Data type name will always be uppercase
  (such as EMPLOYEE OR PERSON_TY).

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Create type address_ty as object (street
varchar2(50), city varchar2(25), state
varchar2(25), zip number) Create type command
note the as object clause. The as object clause
explicitly identifies address_ty as an OO
implementation. Create type person_ty as
object (name varchar2(25), address
address_ty) The following command creates a
table named customer. A customer has a cutomer_id
and all the attributes of a person ( via the
person_ty datatype) create table
customer (customer_id number,person
person_ty) desc customer desc person_ty
desc address_ty
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select column_name,data_type from
user_tab_columns select column_name,data_type
from user_tab_columns where table_name'CUSTOMER'
select attr_name,length,attr_type_name from
user_type_attrs where type_name'PERSON_TY' sele
ct attr_name,length,attr_type_name from
user_type_attrs where type_name'ADDRESS_TY' Ins
erting records into the Customer table insert
into customer values(1, person_ty('Mahesh',address
_ty('Dadar','Mumbai','Maharashtra',416313))) ins
ert into customer values(2, person_ty('Vaishali',a
ddress_ty('Kurla','Mumbai','Maharashtra',416315)))
select customer_id from customer select
from customer select customer_id,client.person.n
ame from customer client
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select client.person.address.street from customer
client select client.person.name,
client.person.address.city from customer client
where client.person.address.city like 'M'