DBMS Data Models

DATA MODELS:-

  • Data Models as the name specifies modelling of data description, data semantics, consistency constraints of the data.
  • Database models define the logical design and structure of the database and defines how data will be stored, what data will be stored, how data will be accessed and updated in the database management system.
  • With the help of data models, data abstraction is achieved for describing the design of the database at each level.1
Types of Data Models:-
  • Hierarchical Models
  • Network Models
  • Entity-Relational Models
  • Relational Model
  1. Hierarchical Models:-In this model data is organised into a tree-like structure. There is one root node and other child nodes connect with the root node . The hierarchy starts from the Root and it expands like a tree adding child nodes to the parent nodes.In this type of model, a child node will only have a one single parent node.






2. Network Models:- Network model is an extension of the Hierarchical model. In this model, data is organised like a graph. In this model, a child can have more than one parent node. In this model, data is more related and more relationships can be established. Data accessing is also easier and fast as the data is more related. This Database model was used to map many-to-many data relationships.




3.Entity-Relationship Model:- An ER model is the logical representation of data as entity and relationships among them. This model was designed by peter Chen and published in 1976 papers. This model is widely used in the design of the database.ER model represent the relationship into a pictorial form to make it easier for a different stakeholder to understand.
for example:- In a school database, Student is an entity and name , age , date of birth are the attributes.



4. Relational Models:- This model was introduced by E.F Codd in 1970, and since then it has been the most widely used database model around the world. In this model data and relationships are represented by collection of inter-related tables. The basic structure of data in this model is the tables. Tables are also known as relations in this model. Each table is a group of column and rows, where column represents attributes of an entity and rows represent records.




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