Database Models

Definition

• Database models are conceptual frameworks that define the structure, relationships, and rules governing how the data is stored, organized, manipulated, and accessed in a database management system (DBMS). 

Types of Database Models

• There are several types of database models exist today but each database model offers various ways to structure data, each with its advantages and best-use cases. These are –

(A) Hierarchical Model

• • The hierarchical database model was popular in the early days of the digital database in the 1950s and 1960s as people transitioned from the paper filing of data. 
  • This model was popular in older systems like IMS (Information Management System) but It’s not a commonly used database model anymore/now. 
  • The hierarchical database model is a very structured form of the model in which data is organized/arranged in a top-down order in a tree-like structure, (where each record has a single parent, except for the root record) with the top of the tree being the top of the hierarchy. 
  • Advantage:
    • Easy insertion and deletion of data according to need.
    • This model is near the natural hierarchy structure.
    • Supports one-to-many relationships.
  • Disadvantages:
    • This model doesn’t support many-to-many relationships.
    • This model is not flexible.
    • Data manipulation is simple due to the difficulty of Query
    • A search operation is slow.
    • Prone to anomalies
    • Not suitable for storing heavy data.

(B) Network Model

• • The network database model is an extended form of the hierarchical model.
  • It was introduced in the late 1960s as a response to the inefficiencies of the hierarchical model.
  • This model is similar to the hierarchical model but allows records to have multiple parent and child records, forming a more complex network.
  • The major inefficiency solved by the network model was the many-to-many relationships that allowed for faster searches. This new efficiency was crucial for businesses.
  • The CODASYL database management system used this model.
  • Advantages:
    • Easy to understand
    • Support heavy data storage hence Business-compatible.
    • Support many-to-many relationships hence fast searching.
  • Disadvantages:
    • Expensive model
    • Inefficient for doing all types of manipulations
    • Prone to anomalies
    • Difficult to modify the records

(C) Relational Model

• • This is the most usable database model in the world now.
  • The relational model is based on the concept of tables (relations) consisting of rows (tuples) and columns (attributes).
  • The relational model organizes data into tables with rows and columns, and uses a query language called SQL (Structured Query Language) to access and manipulate the data.
  • The relational model consists of multiple tables that bear some relationship with each other.
  • It uses keys to establish relationships between tables.
  • Examples of some popular Relational databases are MySQL, PostgreSQL, SQL Server, and Oracle.
  • Advantages:
    • Easy to use
    • Flexible
    • Scalable
    • Precise
    • Secure 
  • Disadvantages:
    • Slow extraction
    • High memory consumption

(D) Entity Relationship Model

• • This model uses entities (objects or concepts) and their relationships to model data.
  • It’s often used to design relational databases and is represented using ER diagrams.
  • The entity-relationship database model is similar to the network model because it shows the relationship between two entities. However, the entity-relationship model displays more detail and allows for additional types of relationship features, known as cardinality.
  • Here, entities are represented with a rectangle and the type of their relationship is represented with a diamond symbol. The type of relationship will always be between the two entities.
  • Advantages:
    • This model has a great visual representation.
    • This model has a simple structure that can be conceptualized.
    • Easily Integrate with relational or other data models.
  • Disadvantages:
    • Having no industry standard for notation.
    • Data manipulation is not represented

(E) Object Oriented Model

• • It treats data as objects, similar to object-oriented programming.
  • It stores objects with attributes and methods and is used in object-oriented databases.
  • Unlike the relational model, the OODB model also supports data such as images.

(F) Document Model

• • This model is used in NoSQL databases like MongoDB, where data is stored as flexible, JSON-like documents rather than rigid tables.
  • It’s suited for handling unstructured or semi-structured data.

(G) Graph Model

• • This model is utilized in graph databases like Neo4j.
  • In this model, data is represented as nodes (entities) and edges (relationships).
  • It’s excellent for analyzing relationships and networks.