What are the commonly used logical models in databases?

What are the commonly used logical models in databases?

The most commonly used logical models in the database field are: hierarchical model (tree diagram), network model (network, graph), and relational model.

1. Hierarchical model:

Advantages:

1. Clear structure, easy to see the relationship between entities

2. Simple operation

3. High query efficiency

Disadvantages:

1. Low structural flexibility. When an entity needs to be updated or modified, it will affect other data

2 .Increases the management burden of DBMS

2. Mesh model:

Advantages:

1.Allows a single node to have more than one parent node

2. There can be two or more nodes without parent nodes

3. Really reflect the real world

Disadvantages:

1. The connection is complex, difficult to implement, and database maintenance Reconstruction is difficult

3. Relational model:

Advantages:

1.Simple and clear structure

2.Strong independence

3. Easy to operate

4. Have a solid mathematical theory as a foundation

Disadvantages:

The query efficiency is lower than that of the hierarchical model, which increases the query burden of the system

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