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.
Types of database management systems
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
- Enforcement of constraints to ensure the data follows the defined rules
A few examples of a DBMS are:
- Computerized library systems
- Automated teller machines (ATMs)
- Flight reservation systems
- Computerized parts inventory systems
- Customer relationship management software
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
Also Read: Best Database Management Software
History of database management systems
Before digital processing, books stored in libraries served as physical databases to store information. Computer database management systems have been developed over the past 60 years:
- In the 1960s, Charles Bachman designed the first computer database. IBM also developed one in the 60s.
- In the 1970s, IBM used its information management system (IMS). Edgar Codd designed the relational database, which organizes data in a table rather than in a hierarchical structure.
- Object-oriented database management systems were largely developed during the 1980s. Object databases feature query languages, which locate objects through declarative programming.
- In the 1990s, object features were integrated into relational databases. The first internet database applications pulled data to web pages. Extensible markup language (XML) was applied to database processing for storing and retrieving XML data.
Characteristics of database management systems
Database management systems:
- Provide security.
- Remove redundancy. Normalization and programmed constraints in relational databases help remove duplicate data.
- Insulate data, known as program-data independence. In a database, a file can be changed once rather than change every program that will access the file.
- Self-describe through metadata, which adds detail about the data that helps users identify it.
- Support multiple views. Information in a database can be viewed in different dimensions, focusing on a different aspect of the data.
- Allow multi-user data sharing
- Create relationships among entities, indicated by pointers
- Employ the ACID concept for processing (atomicity, consistency, isolation, and durability)
- Allow multiple users to enter the database at one time
Advantages and disadvantages of database management systems
Database management systems are:
- Organized, with logical connections between data
- Useful for storing structured data
- Supportive of multiple programming languages
Database management systems also have disadvantages:
- They are not ideal for storing and analyzing large volumes of unstructured enterprise data
- They are not ideal for small businesses that don’t have the budget or IT staff to manage a complex database.
DATABASE MANAGEMENT SYSTEM PROVIDERS
Popular DBMS providers include:(links)