A Database model defines the logical design and structure of a database and defines how data will be stored, accessed and updated in a database management system. Its aim is to give an idea about final system / software predicted appearance after development.
▪ It is a simple abstraction of complex real world data
▪ It defines data elements and relationships among various data elements
“A data model is a way of finding the tools for both business and IT professionals, which uses a set of symbols and text to precisely explain a subset of real information to improve communication within the organization and thereby lead to a more flexible and stable application environment”
Different types of data models are as follows:
Some of the widely known data models are:
Object-Oriented Data Model
Object-Relational Data Model
Flat Data Model
Semi-Structured Data Model
Associative Data Model
Context Data Model
1. To model data description, data semantics, and consistency constraints of the data.
2. To provide the conceptual tools for describing the design of a database at each level of data abstraction.
Hierarchical Data Model
– A hierarchical data model is a model that organizes data in a hierarchical tree structure
– A hierarchical tree structure is made up of nodes and branches
– The dependent nodes are at lower levels in the tree. The hierarchy starts from the Root data, and expands like a tree, adding child nodes to the parent nodes.
Network Data Model
– The network data model interconnects the entities of an enterprise into a network
– It organised more like a graph, and each node/child (in context of above hierarchical model) is allowed to have more than one parent node.
– A block represents an entity or record type. Each record type is composed of zero, one, or more attributes
Relationships or connectors could be of type:
The concept of relationships here is just basic; it
In this database model, relationships are created by dividing objects of interest into entity and its characteristics into attributes. Different entities are related using relationships. Thus its components are: Entities, Attributes, Relationships.
Eg: For a school database:A student entity will have attributes like Student Roll no., Name, address , age, etc. & Entity Course will have attributes like Course ID, Standard & Instructor. Here Course and Student entity will have M:N relationship as many students could be enrolled for one course and each student could enroll into multiple courses.
E-R Models are defined to represent the relationships into pictorial form to make it easier for easy understanding with visualizing.
In this model, data is organised in tables and the relationship is maintained by storing a common field and associating them via Primary Key, Foreign Key concepts..
This model was introduced by E.F Codd in 1970. This is most widely used data model as it is easy to understand and visualize it as well as to implement various operations on it.
The basic structure of data in this model is Relation, that is, tables. All the information related to a particular type is stored in rows of that table. Columns are the attributes of what the table represents information of.