What is a Database Management System?

A database management system is an application used to create and access databases.

Although single user database management systems exist (Microsoft Access for example) these applications are typically used by businesses and larger organizations. Database management systems are also widely used by Internet applications web servers and e-commerce sites.

The Functions of A Database Management System
A typical database management system application has several primary functions:

• Maintain links to data. The database management system is responsible for establishing a physical connection to the data in the database. Users can be on another computer, in another building or even in another country. As long as the connection is maintained, the database can be manipulated from any location.
• Manage access to data. The database management system must control the flow of data to ensure that records are not accidentally garbled. Limiting access to a record to one user at a time is a key requirement. Tracking changes to data records (called transactions) is important in the case of an error or system crash. A database management system provides the ability to undo or "rollback" incomplete or erroneous transactions.
• Maintain data access security. A database management system can limit user access to data. The system can prevent unauthorized access as well as limiting the type of access users may have.

Speaking Your DBMS
Requesting data from a database management system is typically done in the form of a query. A query is a request in the form of a program command. For example: "SELECT ALL WHERE NAME = -RODGERS' AND AGE < 40" tells the database management application to pull all records of people named Rodgers who are under 40 years old.

The most popular programming language used to access database information is the Structured Query Language (SQL). SQL is a powerful, English-like data access language.

More advanced database query languages are called 4GL, or fourth-generation languages.