DBMS (Database Management Systems) is a group of programs used for managing data and concurrently it supports different types of users to create, manage, retrieve, update and store information. It is a software that manages the data for efficient storage and fast retrievals of data from database. MySQL, IBM Db2, Oracle, PostgreSQL etc. are some DBMS softwares that manage the data skilfully.
A Database is a collection of related, logically coherent data used by the application programs in an organization. Database defines, createsandmaintainsadatabase.TheDBMSalso allows controlled access to data in the database. There are four types of DBMS:
Relational Database Management System (RDBMS)
Object Oriented Database Management System.
Hierarchical Database Management System.
Network Database Management System.
1. Relational Database Management System (RDBMS)
In RDMS, data is stored in tables, in form of rows and columns, where a row represent the record of the data and column represents the attributes of the record.
The data is represented as a set of relations.
Arelationappears as a two-dimensional table.
It organizes the data so that its external view is a set of relations or tables.
This does not mean that data is stored as tables.
The physical storage of the data is independent of the way in which the data is logically organized.
A relation in an RDBMS has the features like Name, Attributes, Tuples etc.
In a relational database we can define several operations to create new relations based on existing ones.
2. Object-oriented Database Management System (OODMS)
Object-oriented databases emerged to meet the need of coupling object-oriented programming languages with a database.
It contains the foundational elements like Objects, Attributes and Methods, Classes and Pointers.
It can work with complex data objects.
Works in concert with OOP to facilitate the storage and retrieval of object-oriented data.
Data objects are stored with all of their properties in the database.
When your program terminates, the objects continue to persist, stored in the OOD.
OODs are most often used with object-oriented programming languages like Java, Kotlin, C#, Node JS (React), and Swift. Industries.
3. Hierarchical Database Management System (HDMS)
Hierarchical database is a data model in which data is stored in the form of records.
Data is organized into a tree-like structure, or parent-child structure, in which one parent node can have many child nodes connected through links.
Data is stored in form of one to many relationships. We can visualize it like a tree where a root node is attached to several descendants nodes called leaves.
Each record has a parent ID that lends it to the tree structure. The first record is known as the root record.
To store the data of an organization, the root node is organization itself. The immediate child nodes are: Employees, Managers, Directors.
These child nodes can have further child nodes such as Employees can have child nodes such as: Engineers, Housekeeping staff, system admin etc.
One can access the records by navigating down through the data structure using pointers which are combined with sequential accessing.
4. Network Database Management System (NDMS)
Network Database Management System is based on a network data model.
It allows each record to be related to multiple primary records and multiple secondary records.
Network databases allow us to create a flexible model of relationships between entities.
It is based on a traditional hierarchical database, except it allows each object to have multiple parents instead of a single parent.
Network databases can be represented as a graph instead of a tree structure.
The graph is defined by a schema, which is a list of data nodes and the relationships between them.
This provides a data structure which, in a regular relational database, can only be accessed by inference.
Network databases provide a lot of flexibility, but are still limited to access patterns and design limitations of hierarchical databases.