The three most commonly used data models are hierarchical model, network model and relational model.
1. Hierarchical model
The hierarchical model organizes data into a one-to-many relationship structure. The hierarchical structure uses keywords to access each part of each level.
The hierarchical model was the earliest developed. It uses a tree structure as its basic structure, and its typical representative is the IMS model.
The advantages are convenient and fast access; the structure is clear and easy to understand; data modification and database expansion are easy to implement; and it is very convenient to retrieve key attributes.
2. Network model
The network model uses connection instructions or pointers to determine the explicit connection relationship between data. It is a data organization method with many-to-many types.
The network data model represents the relationship between data through a network structure. It was developed earlier and has certain advantages. It is still widely used. The typical representative is the DBTG model.
The advantage is that it can express complex relationships between data clearly and conveniently.
3. Relational model
The relational model organizes data in the form of record groups or data tables to facilitate storage and transformation using the relationships between various geographical entities and attributes without hierarchical It also has no pointers and is a very effective data organization method to establish the relationship between spatial data and attribute data.
The advantage is that the structure is particularly flexible, the concept is single, and it meets the query requirements formed by all Boolean logical operations and mathematical operation rules; it can search, combine and compare different types of data; it is very convenient to add and delete data.
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