There are four main data models. What are they?

1, hierarchical model

Data is organized into a one-to-many relationship structure, and the relationship between entities is represented by a tree structure.

2. Grid model

It is a many-to-many data organization mode to determine the network connection relationship between data with connection instructions or pointers.

3. Relationship model

Organizing data in the form of record groups or data tables is a very effective data organization method to establish the relationship between spatial data and attribute data, so as to use the relationship between various entities and attributes for storage and conversion.

Extended data

hierarchical model

The hierarchical model organizes data into a one-to-many relational structure, and the hierarchical structure uses keywords to access each part of each level.

Hierarchical model developed earliest, with tree structure as its basic structure, and IMS model is its typical representative.

The advantages are convenient access and high speed; The structure is clear and easy to understand; Data modification and database expansion are easy to realize; It is very convenient to retrieve key attributes.