What kinds of databases are there?

First of all, databases are usually divided into hierarchical databases, network databases and relational databases. Different databases are connected and organized according to different data structures.

Second, the so-called data structure refers to the organizational form of data or the relationship between data.

Third, data structure is divided into logical structure and physical structure of data.

The logical structure of data is to observe and analyze data from a logical point of view (that is, the connection and organization of data), regardless of the storage location of data;

The physical structure of data refers to the structure of data stored in the computer, that is, the realization form of the logical structure of data in the computer, so the physical structure is also called storage structure.

4. The hierarchical structure model is essentially an ordered tree with root nodes ("tree" is mathematically defined as an acyclic connected graph).

5. Database is a warehouse which is built on computer storage equipment and organizes, stores and manages data according to data structure. Simply put, it can be regarded as an electronic filing cabinet-a place to store electronic documents. Users can add, intercept, update and delete data in documents.