To ensure the data independence of the database, what needs to be modified?

To ensure the independence of logical data in the database, what needs to be modified is the image of the schema and the external schema; the schema describes the global logical structure of the data, and the external schema describes the local logical structure of the data; for each Foreign schema, database system has a foreign schema/schema image, which defines the correspondence between the foreign schema and the schema.

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To ensure the independence of logical data in the database, what needs to be modified is the schema and External mode image.

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The schema describes the global logical structure of the data, and the external schema describes the local logical structure of the data.

There can be any number of external modes corresponding to the same mode. For each foreign schema, the database system has a foreign schema/schema image, which defines the correspondence between the foreign schema and the schema. These image definitions are usually included in the description of each mode. When the schema changes, the database administrator makes corresponding changes to each foreign schema/schema image so that the foreign schema remains unchanged. The application program is written based on the external schema of the data, so the application program does not need to be modified, ensuring the logical independence of the data and the program.

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