Database Management System (DBMS), or database program, is software that allows you to create, access, and manage a data in a database. There are many different types of database management systems, ranging from small systems that run on personal computers to huge systems that run on mainframes.
Functions of DBMS:
1. Data Descriptions
DBMS provides a data dictionary. A data dictionary contains data about each file in the database and each field within those files.
2. File Retrieval and Maintenance
A DBMS provides several tools that allow users and programs to retrieve and maintain data in the database. Requests for information from a database are made in the form of a query. A query is a request for specific data from the database. Users can instruct the DBMS to display, print, or store the results of a query. The capability of querying a database is one of the more powerful database features.
1. Data Descriptions
DBMS provides a data dictionary. A data dictionary contains data about each file in the database and each field within those files.
2. File Retrieval and Maintenance
A DBMS provides several tools that allow users and programs to retrieve and maintain data in the database. Requests for information from a database are made in the form of a query. A query is a request for specific data from the database. Users can instruct the DBMS to display, print, or store the results of a query. The capability of querying a database is one of the more powerful database features.
Types of queries:
a. Query Language
A query language consists of simple, English-like statements that allow users to specify the data to display, print, or store.
b. Query by Example
Most DBMSs include a query by example (QBE) feature that has a graphical user interface to assist users with retrieving data. QBE can be thought of as a "fill-in-the blanks" method of query creation.
c. Form
A form, sometimes called a data entry form, is a window on the screen that provides areas for entering or modifying data in a database.
d. Report Generator
A report generator, also called a report writer, allows users to design a report on the screen, retrieve data into the report design, and then display or print the report.
3. Data Security
A DBMS provides means to ensure that only authorized users access data at permitted times. In addition, most DBMSs allow different levels of access privileges to be identified for each field in the database. These access privileges define the actions that a specific user or group of users can perform.
Many organizations practice the Principle of Least Privilege to limit their data access. The principle of least privilege (POLP) is an information security term that refers to a design objective in computing that a given user should only be able to access the information and resources he or she requires for legitimate reasons.
4. Back-up and Recovery
Sometimes database is damaged or destroyed because of hardware failure, a problem with the software, human error, or a catastrophe such as fire or flood. A DBMS provides a variety of techniques to restore the database to a usable form in case it is damaged or destroyed.
Some DBMSs have their own built-in backup utilities. More complex DBMSs maintain a log, which is a listing of activities that change the contents of the database. A DBMS that creates a log usually provides a recovery utility. A recovery utility uses the logs and/or backups to restore a database when it becomes damaged or destroyed and a Continuous backup which is a backup plan in which all data is backed up whenever a change is made.
a. Query Language
A query language consists of simple, English-like statements that allow users to specify the data to display, print, or store.
b. Query by Example
Most DBMSs include a query by example (QBE) feature that has a graphical user interface to assist users with retrieving data. QBE can be thought of as a "fill-in-the blanks" method of query creation.
c. Form
A form, sometimes called a data entry form, is a window on the screen that provides areas for entering or modifying data in a database.
d. Report Generator
A report generator, also called a report writer, allows users to design a report on the screen, retrieve data into the report design, and then display or print the report.
3. Data Security
A DBMS provides means to ensure that only authorized users access data at permitted times. In addition, most DBMSs allow different levels of access privileges to be identified for each field in the database. These access privileges define the actions that a specific user or group of users can perform.
Many organizations practice the Principle of Least Privilege to limit their data access. The principle of least privilege (POLP) is an information security term that refers to a design objective in computing that a given user should only be able to access the information and resources he or she requires for legitimate reasons.
4. Back-up and Recovery
Sometimes database is damaged or destroyed because of hardware failure, a problem with the software, human error, or a catastrophe such as fire or flood. A DBMS provides a variety of techniques to restore the database to a usable form in case it is damaged or destroyed.
Some DBMSs have their own built-in backup utilities. More complex DBMSs maintain a log, which is a listing of activities that change the contents of the database. A DBMS that creates a log usually provides a recovery utility. A recovery utility uses the logs and/or backups to restore a database when it becomes damaged or destroyed and a Continuous backup which is a backup plan in which all data is backed up whenever a change is made.