DBMS DAY 3

DAY -3

Database Model

A Database model defines the logical design of data. The model describes the relationships between different parts of the data. Historically, in database design, three models are commonly used. They are,

• Hierarchical Model
• Network Model
• Relational Model

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       Hierarchical Model

In this model each entity has only one parent but can have several children . At the top of hierarchy there is only one entity which is called Root.

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Network Model

In the network model, entities are organised in a graph,in which some entities can be accessed through several path

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Relational Model

In this model, data is organised in two-dimesional tables called relations. The tables or relation are related to each other.