Notes > Database Systems > Database Management System (DBMS)
A DBMS is a software system that enables users to define, create and maintain a database. The DBMS also enforces necessary access restrictions and security measures in order to protect the database.
The DBMS also has the job of controlling access to database. Various types of control systems within the DBMS make sure that the database continues to function properly:
- Integrity system
- Security system
- Concurrency control system
- Recovery control system
Many DBMSs enable "views" of the database to be defined. A view is how the database appears to a certain user. Views offer the benefit of only having to show relevant information to different types of users and it increases security as certain users will not be able to see data which they are not meant to see. Views can also decrease the perceived complexity of the database from the user's point of view.
Data Definition and Manipulation
The DBMS makes use of a Data Definition Language (DDL) and a Data Manipulation Language (DML). The DML enables the specification of data types, structures and constraints that should be part of the database. All specifications defined by the DDL are stored in the database.
The DML enables those with access to the database to insert, update, delete and retrieve data from it. Structured Query Language (SQL) is the standard DML used today. SQL is a non-procedural language.
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