Database Mangement

DATABASE MANAGEMENT SYSTEM 

What is DBMS?

   DBMS is a software system that manages databases. A database management system (or DBMS) is essentially nothing more than a computerized data-keeping system. Users of the system are given facilities to perform several kinds of operations on such a system for either manipulation of the data in the database or the management of the database structure itself. 

Function of DBMS

Here are some important functions of Database Management System:

1. Data Dictionary Management,
2. Data Storage Management,
3. Data Transformation and Presentation,
4. Security Management,
5. Multi-user Access Control,
6. Backup and Recovery Management,
7. Data Integrity Management,
8. Database Access Languages and application Programming Interfaces and
9. Database Communication interfaces.

Function of DBMS

1. Data Dictionary Management

        Data Dictionary Management is one of the most important functions of the database management system.DBMS stores definitions of the data elements and their relationships (metadata) in a data dictionary.

        So, all programs that access the data in the database work through the DBMS. The DBMS uses the data dictionary to look up the required data component structures and relationships which relieves you from coding such complex relationships in each program.

2. Data Storage Management

        A modern DBMS system provides storage not only for the data, but also for related data entry forms or screen definitions, report definitions, data validation rules, procedural code, structures to handle video and picture formats, and so on.

3. Data Transformation and Presentation

         The DBMS transforms entered data into required data structures. The DBMS relieves you of the chore of making a distinction between the logical data format and the physical data format. That is the DBMS formats the physically retrieved data to make it conform to the user’s logical expectations.

4. Security Management

        Security Management is another important function of Database Management System(DBMS). The DBMS creates a security system that enforces user security and data privacy. Security rules determine which users can access the database, which data items each user can access, and which data operations (read, add, delete, or modify) the user can perform. This is especially important in multiuser database systems.

5. Multi-User Access Control

        Multiuser access control is another important DBMS Function. To provide data integrity and data consistency, the DBMS uses sophisticated algorithms to ensure that multiple users can access the database concurrently without compromising the integrity of the database.  

6. Backup and Recovery Management

          The DBMS provides backup and data recovery to ensure data safety and integrity.

        Current DBMS systems provide special utilities that allow the DBA to perform routine and special backup and restore procedures. Recovery management deals with the recovery of the database after a failure, such as a bad sector in the disk or a power failure. Such capability is critical to preserving the database’s integrity.

7. Data Integrity Management 

        Data integrity management is another important DBMS function. The DBMS promotes and enforces integrity rules, thus minimizing data redundancy and maximizing data consistency.

        The data relationships stored in the data dictionary are used to enforce data integrity. Ensuring data integrity is important DBMS functionality in transaction-oriented database systems.

8. Database Access Language and Application Programming Interfaces

        The DBMS provides data access through a query language. A query language is a nonprocedural language—one that lets the user specify what must be done without having to specify how it is to be done.

        Structured Query Language (SQL) is the defacto query language and data access standard supported by the majority of DBMS vendors.

9. Database Communication Interface

        Current-generation DBMS's accept end-user requests via multiple, different network environments. For example, the DBMS might provide access to the database via the Internet through the use of Web browsers such as Mozilla Firefox or Microsoft Internet Explorer. In this environment, communications can be accomplished in several ways:

        - End users can generate answers to queries by filling in screen forms through their preferred Web browser.

        -The DBMS can automatically publish predefined reports on a Website.

        - The DBMS can connect to third-party systems to distribute information via e-mail or other productivity applications.

ADVANTAGE OF DBMS

1. Improved Data Sharing
   
2. Improved Data Security
3. Better Data Integration
4. Minimized Data Inconsistency
5. Improved Data Access
6. Improved Decision Making
7. Increased End-User Productivity

1. Improved Data Sharing

        An advantage of the database management approach is, the DBMS helps to create an environment in which end users have better access to more and better-managed data.

        Such access makes it possible for end-users to respond quickly to changes in their environment.

2. Improved Data Security

        The more users access the data, the greater the risks of data security breaches. Corporations invest considerable amounts of time, effort, and money to ensure that corporate data are used properly. A DBMS provides a framework for better enforcement of data privacy and security policies.

3. Better Data Integration

        Wider access to well-managed data promotes an integrated view of the organization’s operations and a clearer view of the big picture. It becomes much easier to see how actions in one segment of the company affect other segments.

4. Minimized Data Inconsistency    

        Data inconsistency exists when different versions of the same data appear in different places. For example, data inconsistency exists when a company’s sales department stores a sales representative’s name as “Bill Brown” and the company’s personnel department stores that same person’s name as “William G. Brown,” or when the company’s regional sales office shows the price of a product as $45.95 and its national sales office shows the same product’s price as $43.95. The probability of data inconsistency is greatly reduced in a properly designed database.

5. Improved Data Access    

        The DBMS makes it possible to produce quick answers to ad hoc queries. From a database perspective, a query is a specific request issued to the DBMS for data manipulation—for example, to read or update the data. Simply put, a query is a question, and an ad hoc query is a spur-of-the-moment question. The DBMS sends back an answer (called the query result set) to the application.

6. Improved Decision Making 

        Better-managed data and improved data access make it possible to generate better-quality information, on which better decisions are based. The quality of the information generated depends on the quality of the underlying data. Data quality is a comprehensive approach to promoting the accuracy, validity, and timeliness of the data. While the DBMS does not guarantee data quality, it provides a framework to facilitate data quality initiatives.

7. Increased End-User Productivity

        The availability of data, combined with the tools that transform data into usable information, empowers end users to make quick, informed decisions that can make the difference between success and failure in the global economy.

DISADVANTAGE OF DBMS

1. Increased Costs
2. Management Complexity
3. Maintaining Currency
4. Frequent Upgrade/ Replacement Cycles

1. Increased Costs

         One of the disadvantages of DBMS is 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 regulatory 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. Given the fact that database systems hold crucial company data that are accessed from multiple sources, security issues must be assessed constantly.

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. Vendor dependence. Given the heavy investment in technology and personnel training, companies might be reluctant to change database vendors.

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.