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THERE ARE THREE TYPES OF DBMS
Relational database management system (RDBMS) is the name implies the database management system (DBMS). This adds the added condition of the system which supports tabular structure for the data, with imposed associations between the tables. This eliminates the databases that do not support a tabular structure or do not require relationships between tables.
ü Characteristics of (RDBMS) :
* The data is planned into rows, columns and forming tables.
* Eliminated parent chain relationship and represents data in database as simple row, column tables and data values
* The data can be easily manipulate and altered
* User interface is non procedure DML , since what needs to be done is specified
ü Advantages of (RDBMS):
* Database management system can create different analysis of the same data. Therefore single copies of the data of an organization keep up by an RDBMS meet varied requirement of the people of the organization.
* The attributes that relate table are the only ones that exist in several tables in the database. So Amount of redundancy is minimal.
* The RDBMS supports different level of access. User must be given permission to only view the particular tables and fields. Another user may have open view permissions. Yet another user may have permission to modify particular tables. There may be a user who can modify the structure of the database by modifying a table, or by adding a new table etc. data through an RDBMS can be shared without compromising the security of the data.
* An RDBMS support atomicity through its recovery and rollback mechanism. The data is maintained in a consistent state even if some errors and failures occur.
* An RDBMS make available facilities to select the relevant data and render it on the screen in the preferred format. RDBMS can current stored data to the user as a table , chart or report. The information from the data can be easily extracted.
* An indirect advantage of an RDBMS is that the association can enforce values in naming and documents. It becomes easy for the management to interpret report of various departments if they all follow the same standards.
* An RDBMS contains description of the data which is known as metadata.
ü Disadvantages of RDBMS:
* Hardware overheads: The RDBMS needs moderately powerful hardware as its hides the implementation complexities and the physical data storage details from the users. With the modern day computers, increased power is not a big issue.
* Ease of design can results in bad design: relational database is an easy to use and easy to design the system, it can results in the development and implementation of badly designed database management system. The size of the database increases, several problems may creep in system slowdown, performance degradation and data corruption.
* Information island phenomenon: As the relational database systems are easy to implement and use, departments may create their own application as well database. This situation might delay information integration that is necessary for the smooth and efficient functioning of the organization. Problem like data inconsistency, data duplication and data Redundancy may also crop up.
This system simply puts an object oriented front end on a relational database .the system will convert the object information into data tables with rows and columns and handle the data the same as a relational database.
Today, modern database applications need to store and manipulate objects that are neither small nor simple, and to perform operation on these multimedia objects that are not predefined.
ü Characteristics of(ORDBMS):
* base data type extension
* support complex objects,
* Rule systems.
* user defined structured types
* reference type
* collections are well-typed
ü Advantages of (ORDBMS):
* Resolving the weaknesses of RDBMS
* Reduce network traffic
-reuse comes from ability to extend server to perform standard functionality centrally;
-gives rise to increased productivity both for developer and end-user
* Improved application and query performance
* Simplified software maintenance
* Perseverance of the significant body of knowledge and experience that has gone into developing relational application.
* Integrated data and transaction management
Disadvantages of (ORDBMS):
* Complexity and associated increased costs.
* Loss of simplicity and purity of the relational model due to extension of complex objects.
* Large semantic gap between object oriented and relational technologies.
Ref: database system: concepts, design and applications by s.k.singh
* Increased costs.
* SQL now extremely complex
Ref: fundamentals of relational database management system by s.sumathi , s.esakkirajan
3.1.3 - OODBMS:
The object oriented database management system is the most recent approaches to database management .they started in the engineering and design domain applications and became the favored system for financial, telecommunication and the World Wide Web application. It is suited for multimedia application as well as data with complex relationships that are difficult to model and process in a relational DBMS.
Ref: database system: concept, design and application by s.k. singh
The main characteristic of object oriented database is the integration of object oriented programming with database tools.
ü Characteristics of OODBMS :
* Data encapsulation :
It is allows programmers to hide from view the inside condition of object.
Is allows programmers define share pattern operation and an object operation with further objects.
* Object characteristics:
It allows database object to independent of every one
It allows developing solution by defining of new objects
ü Advantages of OODBMS
* All operation are defined once and reuse by all applications
* Changes to an operation affect all applications , simplifying database maintenance
ü Disadvantages of OODBMS
* Lack of experience :
In comparison to RDBMS the use of OODBMS is still relatively limited .this means that we do not yet have the level of experience that we have with traditional systems.
Perhaps one of the most significant issues that face OODBMS vender is the competition posed by the RDBMS and the emerging ORDBMS products.
The increased functionality provided by an OODBMS, such as illusion of a single-level storage model, pointer swizzling, long-duration transaction, version management and schema evolution, is inherently more complex than those traditional DBMSs. In general complexity leads to product that are more expensive to buy and more difficult to use.
* Lack of support for views
Currently, most OODBMSs do not provide a view mechanism, which as we have seen previously many advantages such as data independence, security, reduced complexity and customization.
* Lack of support for security
Currently OODMSs do not provide adequate security mechanisms. most mechanisms are based on a coarse granularity , and the user con not grant access rights on individual objects or classes. if OODBMSs are to expand fully into the business field. This shortage must be rectified.