object oriented database management
TRANSCRIPT
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Object Oriented
DatabaseByRASHMI RAMESH
III Year Chemical EngineeringNIT Trichy
10211205508th October 2014
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Database Management System
Clients (Services or applications) interact withdatabases through queries (remote or
otherwise) to Create, Retrieve, Update andDelete (CRUD) data within a database. Thisprocess is facilitated through a Database
Management System (DBMS)
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Database Management System
Provides tools for maintenance such as runningsecurity checks, ensuring data integrity, backup
and recovery.
Applications : In all sectors of the modern worldbe it in technology oriented companies orhospitals and health care systems.
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Data Models (Contd.)
Hierarchical model
This supports parent-child relationships between data similarto a tree data structure where object types are represented bynodes and their relationships are represented by arcs.
This model is restrictive in that it only allows one to many
relationship ( a parent can have many children but a child canonly have one parent)
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Data Models (Contd.)Object Model
Reduces the overhead of converting informationrepresentation in the database to an application specificrepresentation.
Allows for data persistence and storage by storing objects inthe databases.
The relationships between various objects are inherent in the
structure of the objects. This is mainly used for complex data structures such as 2D and
3D graphics which must otherwise be flattened before storagein a relational database.
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Object Model
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Object Oriented DatabaseManagement Systems (OODMs)
Object database management systems extend the objectprogramming language with transparently persistent data,concurrency control, data recovery, associative queries, andother database capabilities.
Thus OODB implements OO concepts such as object identity,
polymorphism, encapsulation and inheritance to provideaccess to persistent objects using any OO-programminglanguage
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Objects User defined complex data types. An object has structure or state (variables) and methods
(behavior/operations). An object is described by four characteristics
Identifier: a system-wide unique id for an objectName: an object may also have a unique name in DB(optional)Lifetime: determines if the object is persistent or transient
Structure: Construction of objects using type constructors The state (current value) of a complex object may be
constructed from other objects (or other values) by usingcertain type constructors.
Objects (Contd.)
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Objects (Contd.) An object is associated with it:
A set of variables that contain the data for the object.The value of each variable is itself an object.
A set of messages to which the object responds; eachmessage may have zero, one, or more parameters.A set of methods , each of which is a body of code toimplement a message; a method returns a value as the
response to the message Messages and responses provide the only external interface to
an object.
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Need for Complex Data Types
Addresses can be viewed as a Single string Separate attributes for each part, or Composite attributes
(which are not in first normal form) Convenient to store multivalued attributes as-is, without
creating a separate relation to store the values in first normalform
Applications :
computer-aided design, computer-aided software engineeringmultimedia and image databases, and document/hypertextdatabases.
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Features Of OODMs
New features relational & Object oriented
Relational Features new data types, newpredicates, enhanced semantics, additionalsecurity and an active database.
Object Oriented Features support for functionsand procedures.
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Relational and Object Models Queries look very similar in SQL and OQL, sometimes they are
the same In fact, the results they give are very different Query returns:
OQL - ObjectSQL - Collection of objects, Tuple, Table
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Relational and Object Models(Contd.)
A method in an object model is defined in the class to whichthe object belongs.
A stored procedure is a sub-routine available to applicationsand this is external to the database , defined in the datadictionary.
Example: Stored procedures for data validation OODB is OO language specific whereas Relational DB are
language independent via SQL No impedance mismatch in applications using OODB where as
object relational mapping must be performed in relationaldatabase for use in OO applications.
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Object Query Language
Example of OQL with integration to OO Language: Create objects as in OO languages and then make them
persistent using the set() method on the database.
Person p1 = new Person(Pikes Peak", 78); db.set(p1); Retrieve by age (null default for string)
Person p = new Person (null, 35); ObjectSet result = db.get(p);
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Thank You