Data modelling concepts in data warehousing

There are four major types of data modelling concepts are available.
Conceptual data model
This data model type would be starting point of building a database when knowing only business object or entity level information which is required for business. It just has the list of objects and linking between objects.

Conceptual Data Model
For example, when a retail shop wants to build a data mart, at first level they don’t have information about fields and referential integrity information. The lists of objects required are location, category and sales.
The relationship between these three entities as mentioned in the image.
Logical data model
This type of data model contains,
  1. List of attributes will be captured for all entities
  2. Primary key will be defined for all entities
  3. Reference key will be defined between entities
Logical Data Model
Physical data model
A physical data model contains,
  1. Tables with primary key
  2. Tables will be linked with foreign key
  3. All columns will have data type and length
Physical Data Model
Dimensional data model
There are two types of schema building approach based on the concept of dimension and fact table,
  1. Star schema
  2. Snow flake schema