Disadvantages of Database Management System

Posted by Ripon Abu Hasnat on Monday, June 16, 2014 | 0 comments | Leave a comment...



Although the database system yields considerable advantages over previous data management approaches, database systems do carry significant disadvantages. These are-

1. Increased costs.
Database systems require sophisticated hardware and software and highly skilled personnel. The cost of maintaining the hardware, software, and personnel required to operate and manage a database system can be substantial. Training, licensing, and regulation compliance costs are often overlooked when database systems are implemented.

2. Management complexity.
Database systems interface with many different technologies and have a significant impact on a company’s resources and culture. The changes introduced by the adoption of a database system must be properly managed to ensure that they help advance the company’s objectives.

3. Maintaining currency.
To maximize the efficiency of the database system, you must keep your system current. Therefore, you must perform frequent updates and apply the latest patches and security measures to all components. Because database technology advances rapidly, personnel training costs tend to be significant. Given the heavy investment in technology and personnel training, companies might be reluctant to change database vendors. As a consequence, vendors are less likely to offer pricing point advantages to existing customers, and those customers might be limited in their choice of database system components.

4. Frequent upgrade/replacement cycles.
DBMS vendors frequently upgrade their products by adding new functionality. Such new features often come bundled in new upgrade versions of the software. Some of these versions require hardware upgrades. Not only do the upgrades themselves cost money, but it also costs money to train database users and administrators to properly use and manage the new features.

5. Cost of Hardware & Software:
A processor with high speed of data processing and memory of large size is required to run the DBMS software. It means that you have to upgrade the hardware used for file-based system. Similarly, DBMS software is also Very costly.

6. Appointing Technical Staff:
The trained technical persons such as database administrator and application programmers etc are required to handle the DBMS. You have to pay handsome salaries to these persons. Therefore, the system cost increases.

7. Database Failures:
In most of the organizations, all data is integrated into a single database. If database is corrupted due to power failure or it is corrupted on the storage media, then our valuable data may be lost or whole system stops.

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Advantages of Database Management System

Posted by Ripon Abu Hasnat on | 0 comments | Leave a comment...



The DBMS has a number of advantages as compared to traditional computer file processing approach. The DBA must keep in mind these benefits or capabilities during designing databases, coordinating and monitoring the DBMS. The major advantages of DBMS are described below.


1. Controlling Data Redundancy:
In non-database systems (traditional computer file processing), each application program has its own files. In this case, the duplicated copies of the same data are created at many places. In DBMS, all the data of an organization is integrated into a single database. In DBMS, the data redundancy can be controlled or reduced but is not removed completely.


2. Data Consistency:
By controlling the data redundancy, the data consistency is obtained. If a data item appears only once, any update to its value has to be performed only once and the updated value (new value of item) is immediately available to all users.

3. Data Sharing:
In DBMS, data can be shared by authorized users of the organization. The DBA manages the data and gives rights to users to access the data. Many users can be authorized to access the same set of information simultaneously. The remote users can also share same data. Similarly, the data of same database can be shared between different application programs.

4. Data Integration:
In DBMS, data in database is stored in tables. A single database contains multiple tables and relationships can be created between tables (or associated data entities). This makes easy to retrieve and update data.

5. Integrity Constraints:
Integrity constraints or consistency rules can be applied to database so that the correct data can be entered into database. The constraints may be applied to data item within a single record or they may be applied to relationships between records.

6. Data Security:
Data security is the protection of the database from unauthorized users. Only the authorized persons are allowed to access the database. Some of the users may be allowed to access only a part of database i.e., the data that is related to them or related to their department.
Most of the DBMSs provide the security sub-system, which the DBA uses to create accounts of users and to specify account restrictions. The user enters his/her account number (or username) and password to access the data from database.

7. Data Atomicity:
A transaction in commercial databases is referred to as atomic unit of work. For example, when you purchase something from a point of sale (POS) terminal, a number of tasks are performed such as;
Company stock is updated.
Amount is added in company's account.
Sales person's commission increases etc.

8. Database Access Language:
Most of the DBMSs provide SQL as standard database access language. It is used to access data from multiple tables of a database.

9. Development of Application:
The cost and time for developing new applications is also reduced. The DBMS provides tools that can be used to develop application programs. For example, some wizards are available to generate Forms and Reports. Stored procedures (stored on server side) also reduce the size of application programs.

10. Creating Forms:
Form is very important object of DBMS. You can create Forms very easily and quickly in DBMS, Once a Form is created, it can be used many times and it can be modified very easily. The created Forms are also saved along with database and behave like a software component.

11. Report Writers:
Most of the DBMSs provide the report writer tools used to create reports. The users can create reports very easily and quickly. Once a report is created, it can be used many times and it can be modified very easily. The created reports are also saved along with database and behave like a software component.

12. Control Over Concurrency:
In a computer file-based system, if two users are allowed to access data simultaneously, it is possible that they will interfere with each other. Most DBMSs have sub-systems to control the concurrency so that transactions are always recorded" with accuracy.

13. Backup and Recovery Procedures:
In a computer file-based system, the user creates the backup of data regularly to protect the valuable data from damaging due to failures to the computer system or application program. It is a time consuming method, if volume of data is large. Most of the DBMSs provide the 'backup and recovery' sub-systems that automatically create the backup of data and restore data if required.

14. Data Independence:
In computer file-based system, the structure of data items is built into the individual application programs. Thus the data is dependent on the data file and vice versa.

15. Advanced Capabilities:
DBMS also provides advance capabilities for online access and reporting of data through Internet. Today, most of the database systems are online. The database technology is used in conjunction with Internet technology to access data on the web servers.

16. Flexibility:
Because programs and data are independent, programs do not have to be modified when types of unrelated data are added to or deleted from the database, or when physical storage changes.

17. Lower user training costs:
Users often find it easier to learn such systems and training costs may be reduced. Also, the total time taken to process requests may be shorter, which would increase user productivity.

18. Data abstraction:
The property of DBMS that allows program-data independence is known as data abstraction. Data abstraction allows the database system to provide an abstract view of the data to its users without giving the physical storage and implementation details.

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Define Database management system (DBMS)

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A database management system is the software system that allows users to define, create and maintain a database and provides controlled access to the data.

A Database Management System (DBMS) is basically a collection of programs that enables users to store, modify, and extract information from a database as per the requirements. DBMS is an intermediate layer between programs and the data. Programs access the DBMS, which then accesses the data. There are different types of DBMS ranging from small systems that run on personal computers to huge systems that run on mainframes. The following are main examples of database applications:

Computerized library systems
• Automated teller machines
• Flight reservation systems
• Computerized parts inventory systems

A database management system is a piece of software that provides services for accessing a database, while maintaining all the required features of the data. Commercially available Database management systems in the market are dbase, FoxPro, IMS and Oracle, MySQL, SQL Servers and DB2 etc.

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