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Data
model –The data model is fundamental representing information. The
data model determine what data representation mechanism are supported by the
DBMS. The data definition language is just the specific set of language
construct available to describe an actual applications data in term of the data
model.
OR
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. While the Relational
Model is the most widely used database model.
Types of
database models - There are many
kinds of data models. Some of the most common ones include:
·
Hierarchical database model
·
Relational model
·
Network model
·
Object-oriented database model
·
Entity-relationship model
·
Document model
·
Entity-attribute-value model
·
Star schema
·
The object-relational model, which combines the two
that make up its name
1. Hierarchical
model –
·
This database
model organises data into a tree-like-structure, with a single root, to which
all the other data is linked.
·
The hierarchy
starts from the Root data, and expands like a tree, adding child
nodes to the parent nodes.
·
In this
model, a child node will only have a single parent node.
·
In
hierarchical model, data is organised into tree-like structure with one
one-to-many relationship between two different types of data, for example, one
department can have many courses, many professors and of-course many students.
2.
Network model –
·
This is an
extension of the Hierarchical model.
·
In this model data is organized more like a
graph, and are allowed to have more than one parent node.
·
In this
database model data is more related as more relationships are established in
this database model.
·
This database model was used to map
many-to-many data relationships.
·
This was the
most widely used database model, before Relational Model was introduced.
3.
Relational Model –
·
In this
model, data is organized in two-dimensional tables and the
relationship is maintained by storing a common field.
·
The basic
structure of data in the relational model is tables.
·
All the information related to a particular
type is stored in rows of that table.
·
Hence, tables
are also known as relations in relational model.
