What are the global logical structures and characteristics that describe the entire data in the database?

What is the global logical structure and characteristics that describe the entire data in the database?

In the three-level schema structure of the database, the "schema" describes the global logical structure and characteristics of all data in the database.

The three-level schema structure of the database means that the database system consists of three levels: external schema, schema and internal schema. External schema, also called sub-schema or user schema, is a description of the logical structure and characteristics of local data that database users can see and use. It is a database user's data view and a logical representation of data related to a certain application. Schema, also called logical schema, is a description of the logical structure and characteristics of all data in the database and is a common data view for all users. The internal schema is also called the storage schema, which is a description of the physical structure and storage method of data.

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