What are the three main types of DBMSs, according to the traditional…

Database Management Systems (DBMSs) are classified based on their underlying data model — the way data is logically structured and how relationships between records are represented. The classical/traditional classification, taught across DBMS fundamentals courses and commonly tested in exams, recognizes three primary data models: relational, hierarchical, and network.

1. Relational DBMS (RDBMS):
   A Relational DBMS stores data in the form of tables containing rows and columns. Relationships between tables are created using keys. It is the most widely used DBMS today because of its simplicity, flexibility, and efficiency.

Examples: MySQL, PostgreSQL, Oracle Database

1. Hierarchical DBMS:
   A Hierarchical DBMS organizes data in a tree-like structure where each parent can have multiple child records, but each child has only one parent.

Example: IBM IMS.

1. Network DBMS:
   A Network DBMS organizes data in a graph-like structure. Unlike the hierarchical model, a child record can have multiple parent records, allowing many-to-many relationships.

Example: Integrated Data Store (IDS).

Why the other offered combinations do not fit the traditional three-type classification:

• Object-Oriented DBMSs are a modern, specialized model developed later to handle complex objects; they are not part of the classical three-type classification.

• NoSQL DBMSs are also a newer category of database systems designed for big data, distributed systems, and unstructured data; they became popular much later and are not considered part of the foundational three DBMS models.

Therefore, the classical/traditional grouping — relational, hierarchical, and network DBMSs — is the correct answer among the options offered. Modern extensions such as object-oriented and NoSQL DBMSs are taught as later additions to this base classification, not replacements for it — which is why they are excluded from the traditional “three main types” grouping.