What Is Meant By Database Management System ?

Database management system is a software system (set of programs) that is used for the management of databases. Now to understand Database management system it is necessary to know about databases.

  Database is a data structure used to organize related data. In databases data is stored in such a way that it can be easily accessed and changed easily. Normally a database is a collection of tables. A table itself can also be called as database and Table is a collection of columns and rows. Each row contains some type of information about an entity. Consider the following example:
    
Record No    Name      Age     Profession
    1         Imran     26   Teacher

In the database terminology each row is called a record and each column is called as field.
Databases provide an easy way to store and manipulate data. Data redundancy or duplication can be easily controlled in databases. Database management systems provide different facilities to access and manipulate the data stored in the databases. In the file system several copies of the same data can exist but database management system does not allow this. Another advantage of database system is that it either allows a full transaction or it does not allow it at all. For example, if a person wants to withdraw some money from the bank and then the whole transaction will follow following steps:

  1. Give money to the account holder
  2. Subtract that amount from his account.
Now if there is some case that after that first step ATM machine fails then there is a chance of inconsistency but DBMS controls this situation in such a way that the whole transaction is aborted.

Any programming environment, which is used to create containers for managing human data can be called Database Management System or DBMS. A database is the management of a block of human data.

A Database Management System represents complex relationship between data and keeps a control of data redundancy. A Database Management System shares data across the applications and enforces the data access authorization. A Database Management System has a centralized data dictionary for the storage of information pertaining to data and its manipulation. It implies the data integrity by using the user define rules. A DBMS can be used via different interfaces to manipulate the data. A Database Management System can be used by multiple user are the same time.

All database management systems (e.g. Oracle, SQL server) allow users to create containers for data storage and management. These containers are called cells. The cells has its Name, Length and the Type of data that be inserted in the cell (also called field). Multiple fields grouped in the same plane are called a Record. Several records of similar length, which are placed one below to the other is called a table. A group of tables with related data is called a Database.

A database is a collection of interrelated information. This information is saved in a very organized manner. By using this known structure, we can access and
change the information quickly and correctly. In this information era, databases are everywhere. When we go to the library and look up a books on their computer, we are accessing the library's book database. When we go on-line and acquire some product, we are accessing the web merchant's product database. Our bank keeps all our financial records on their database.

When we receive our monthly statement, the bank generates a report from database. When we call to make a doctor appointment, the receptionist looks into their database for available times. When we go to our car dealer for repairs, the technician calls up our past work record on the garage database. At the General store, when the checker scans each product, the price is found in the store's database against that item, where inventory control is also performed.

We can definitely think of many more position that databases enter our life. The general thought is that they are everywhere. And, each database needs some way for a user to interrelate with the information within. Such communication is performed by a database management system (DBMS).

DBMS (Data Base Management System): Is a system or computer software that is designed for the purpose to manage information or databases in such way so that data storage and retrieval of information gets easy, so we can easily say that DBMS defines what will be the structure for information storage and in addition to it facilitates in data manipulation. The common examples of Data Base Management Systems are Microsoft Access, DB2, Oracle, SQL Server etc. There are some common goals while using DBMS.

(1) Security.
(2) Backup and Replication.
(3) Change and Access Logging.
(4) Automated Optimization.
(5) Policy Enforcement.
(6) Query Ability.
(7) Meta Data Repository.
(8) Computation.
There are three most commonly used database models.
(1) Hierarchal.
(2) Network.
(3) Relational.

The above mentioned database models totally depends on the requirement and complexity of organizations data. But generally the most widely accepted database model is the relational database model which uses tables for data storage and the relationship among the data in different tables is also managed through this database model. The size of the database depends on the requirement of the user it could be in Megabytes or Gigabytes or it could be in Terabytes. There are many techniques which are used for data backup and fast access e.g. RAID (Redundant Array of Independent Disks) in which data is replicated on different disks so in case if one of the disk gets corrupted or damaged the data can be accessed from the other disk.

Typically database management system is considered as a computerized record keeping system. However, DBMS is a collection of programs, which are used to define, create and maintain databases. Basically, DBMS is a general-purpose software package whose overall purpose is to maintain information and to make that information available on demand. You can also develop a special purpose DBMS software (in Visual Basic, C++ etc.) to create and maintain databases.

There are many functions of general-purpose DBMS software but the main functions are:
(i)         Defining the Structure of Database: which involves defining tables
and their relationships, fields and their data types and constraints for data to be stored in the database.
(ii)       Populating the Database: which involves to store data into database.
(iii)      Manipulating the Database: which involves to retrieve specific data. update data, delete data, insert new data, and to generate reports.

Now consider the example of university computer file-based processing system , which is converted to database management system , All of the data about applicants, students, courses, and faculty is stored in a single file called database. The data is integrated into database. It means that the data items are stored in a compatible format and logical connection among them is also stored.

The database contains a description of its own structure so that the DBMS "knows" what data items exist and how they are related to each other. Many users can share the database through the DBMS. The DBMS also provides a user-interface for online queries. The users can access the database directly from terminals, using the query language such as SQL statements.

Does data base structure relate with data base management