A database management system (DBMS) is software that handles the storage, retrieval, and updating of data in a computer system. It serves as an interface between the end user and the database and manages the data, database engine, and database schema to facilitate the organization and manipulation of data. A DBMS will define rules and manipulate the data format, field names, record structure, and file structure itself.
Database management systems differ in how information is internally organized. Internal organization affects how quickly and flexibly information can be extracted. While there are many types of DBMS, four common ones include:
- Hierarchical: Data is modeled in a tree-like structure. Data is stored hierarchically and is represented by using a parent-child relationship. While the parent may have many children, children have only one parent.
- Network: This model allows each child to have multiple parents. This addresses the need to model complex relationships. Entities are organized in a graph that can be addressed through several paths.
- Relational: This model is the most commonly used because it’s the most user friendly. The model is based on normalizing data in rows and columns of the tables and is stored in a fixed structure.
- Object-oriented: Data is stored in the form of objects. It defines a database as a collection of objects that stores both data members values and operations.
Examples of a database management system
Functions of a DBMS include a user accessible catalog, library management system, data abstraction and independence, data security, logging and auditing of activity, support for authorization of access, data recovery, and enforcement of constraints to ensure the data follows the defined rules.
A few examples of a DBMS are:
- Computerized library systems
- Automated teller machines
- Flight reservation systems
- Computerized parts inventory systems
In a more specific example, consider a university database system. The database consists of information concerning students, courses, and grades. Files within the database system include:
- The student file stores data of each student
- The course file stores data of each course
- The section file stores data about sections within a particular course
- The grade file stores data about the grades students receive
- The tutor file stores data about each professor
Database management system providers
Popular DBMS providers include:
- Microsoft SQL Server
- Oracle Database
- IBM Db2