Database model

It is the description of the data in a database. In addition data model describes the relationship among data and any constraints that have to be defined on the data. There are two type of data model that is Record based logical model and object based logical model.

Record based logical model-:

It also describe data at the conceptual and view levels. These models specify logical structure of info with records, fields and attributes.

There are three types 

1. Network model
2. Relational model
3. Hierarchical Model

Network model-:Network Model is same as hierarchical model except that it’s graph-like structure rather than a tree-based structure. Unlike hierarchical model, this model allows each record to have more than one parent record.
Relational model-: In relational model, the data and relationships are represented by collection of inter-related tables. Each table could be a cluster of column and rows, where column represents attribute of an entity and rows represents records.
Hierarchical model-: In hierarchical model, data is organized into a tree like structure with each record is having one parent record and many children. The main disadvantage of this model is that, it can have only one to many relationships between nodes.

Object based logical model-: 

It is used to describe data at the conceptual and view levels.

There is one type of Object based logical model

1. ER model (Entity-relationship Model)

ER model- An entity–relationship model (ER model) is a systematic way of describing and defining a business process. An ER model is typically implemented as a database.
The main elements of E-R model are: entity set and relationship set.

Here are the geometric shapes and their meaning used in an E-R Diagram –

Rectangle: Represents Entity sets.
Ellipses: Attributes
Diamonds: Relationship Set
Lines: They link attributes to Entity Sets and Entity sets to Relationship Set
Double Ellipses: Multivalued Attributes
Dashed Ellipses: Derived Attributes
Double Rectangles: Weak Entity Set
Double Lines: Total participation of associate degree entity in a very relationship set