E-R MODEL:

The Entity-Relationship model is based on a perception of the world as a collection of basic objects(entities) and relationships amongh these objects.

RELATIONAL MODEL:

Data and Relationships are represented by a collection of tables.Each table has a number of columns with unique names.For example:customer,account.

NETWORK MODEL:

Data are represented by collection of records.Relationships among data are represented by links.Organization is that of an arbitrary graph.

HIERARCHICAL MODEL:

The hierarchical model is similar to the network model.Organization of the records is like a collection of trees,rather than arbitrary graphs.