DATABASE MANAGEMENT SYSTEM

 Database Management System (DBMS)

is a set of computer programs that controls the creation, maintenance and the use of a database.

It allows organizations to place control of database development in the hands of database administrators (DBAs) and other specialists. 

A DBMS is a system software package that helps the use of integrated collection of data records and files known as databases. 

 In large systems, a DBMS allows users and other software to store and retrieve data in a structured way.  

 Common use of a database system is to track information about users, their name, login information, various addresses and phone numbers. 

Instead of having to write computer programs to extract information, user can ask simple questions in a query language.

So what is query language???

allows users to interactively interrogate the database, analyze its data and update it according to the users privilages on data. 

It also controls the security of the database. 

Data security prevents unauthorized users from viewing or updating the database. 

Using passwords users are allowed access to the entire database or subsets of it called subschemas. 

For example an employee database can contain all the data about an individual employee but one group of users may be authorized to view only payroll data, 

while others are allowed access to only work history and medical data.  

There are some standard functions of a DBMS that can be shared:

The ability to update and retrieve data

This is a fundamental component of a DBMS and essential to database management. Without the ability to view or manipulate data, there would be no point to using a database system.

Updating data in a database includes adding new records, deleting existing records and changing information within a record.

Support Concurrent Updates

Concurrent updates occur when multiple users make updates to the database simultaneously. Supporting concurrent updates is also crucial to database management as this component ensures that updates are made correctly and the end result is accurate. Without DBMS intervention, important data could be lost and/or inaccurate data stored. DBMS uses features to support concurrent updates such as batch processing, locking, two-phase locking, and time stamping to help make certain that updates are done accurately.

Recovery of Data

In the event a catastrophe occurs, DBMS must provide ways to recover a database so that data is not permanently lost. There are times computers may crash, a fire or other natural disaster may occur, or a user may enter incorrect information invalidating or making records inconsistent. If the database is destroyed or damaged in any way, the DBMS must be able to recover the correct state of the database, and this process is called Recovery. The easiest way to do this is to make regular backups of information.