What is Database ?
A database is a set of related data. In simple words, a database is a collection of data which has been organized so that a computer program can quickly select desired items. By data, we mean known facts that can be recorded and have an implicit meaning.
The basic type of database we used is the traditional database which has data in the form of text and numbers. But with the advancement in the Computer and Communication Technology we have new types of databases. Multimedia databases where data includes pictures, video clips and audio along with text; Geographic Information Systems which has data about satellite pictures and weather images; Data warehousing and Online Analytical Processing where some historical data is analyzed using statistical tools which can be used for decision making. For information about data warehouse, please read
Data Warehouse – Definition, Properties and Benefits
Though there are different databases for various applications, it is important to get to the basics of the database concepts. In this article I will try to give an introduction of database and database system.
File – Based System :
Earlier organizations were storing data as part of File Systems which is a collection of application programs that perform services for the end users (e.g. reports).In such cases each program defines and manages its own data.
Limitations of File-Based System :
- Separation and isolation of data : Each program maintains its own set of data. So users of one program may be unaware of potentially useful data held by other programs.
- Duplication of data : Same data is held by different programs. Space is wasted. Same item can have potentially different values and/or different formats.
- Data dependence : File structure is defined in the program code.
- Incompatible file formats : Programs are written in different languages, and so cannot easily access each other’s files.
- Fixed Queries/Proliferation of application programs : Programs are written to satisfy particular functions. Any new requirement needs a new program.
Database Management Systems (DBMS) :
A Database Management System (DBMS) is a software system that enables users to define,
create, maintain, and control access to the database –
where defining a database means identify the data in terms of data types, structures and
constraints; constructing the database means to load it on a secondary storage medium;
manipulating the database means querying, generating reports, insertions, deletions and
modifications to its content.
It is assumed that operations (update, insert, retrieve, etc.) on the database can be carried out in a simple and flexible way. Also since a database tends to be a long term resource of an organization, it is expected that planned as well as unplanned applications can (in general) be carried out without great difficulty.
So a Database System consists of a:
- Data definition language (DDL) : This permits specification of data types, structures and any data constraints. All specifications are stored in the database.
- Data manipulation language (DML) : This contains the general enquiry facility (query language) of the data.
Features Of Database Management System (DBMS) :
- Self-describing nature of a database system: A DBMS catalog stores the description of the database (this description is called meta-data). This allows the DBMS software to work with different databases.
- Insulation between programs and data: Called program-data independence. Allows changing data storage structures and operations without having to change the DBMS access programs
- Data Abstraction: A data model is used to hide storage details and present the users with a conceptual view of the database.
- Support of multiple views of the data : Each user may see a different view of the database, which describes only the data of interest to that user.
- Sharing of data and multiuser transaction processing : allowing a set of concurrent users to retrieve and to update the database. Concurrency control within the DBMS guarantees that each transaction is correctly executed or completely aborted. OLTP (Online Transaction Processing) is a major part of database applications.
Advantages of Database Management System :
- Control of data redundancy
- Data consistency
- More information from the same amount of data
- Sharing of data
- Improved data integrity
- Improved security
- Enforcement of standards
- Economy of scale
- Balance conflicting requirements
- Improved data accessibility and responsiveness
- Increased productivity
- Improved maintenance through data independence
- Increased concurrency
- Improved backup and recovery services
Functions Of DBMS :
- Data storage, retrieval and update : A DBMS provides users with the ability to store, retrieve and update data in the database.
- A user-accessible catalog : A DBMS provides a catalog in which descriptions of data items are stored and which is accessible to users.
- Transaction support : A DBMS provides a mechanism which will ensure either that all the updates corresponding to a given transaction are made or that none of them is made.
- Concurrency control services : A DBMS provides a mechanism to ensure that the database is updated correctly when multiple users are updating the database concurrently.
- Recovery services : A DBMS provides a mechanism for recovering the database in the event that the database is damaged in any way.
- Authorization services : A DBMS provides a mechanism to ensure that only authorized users can access the database.
- Support for data communication : A DBMS must be capable of integrating with communication software
- Integrity services : A DBMS provides a means to ensure that both the data in the database and changes to the data follow certain rules.
- Services to promote data independence : A DBMS provides facilities to support the independence of programs from the actual structure of the database.
So this was an introduction to database and database system. Hope you will get good understanding about the database after reading this.
To know about the types of databases, you can read – Types Of Databases
Thanks for reading.