Three-schema approach

The notion of a three-schema model was first introduced in 1975 by the ANSI/X3/SPARC three level architecture, which determined three levels to model data.[1]

Image of the six layers in the Zachman Framework.

The three-schema approach, or three-schema concept, in software engineering, is an approach to building information systems and systems information management that originated in the 1970s. It proposes three different views in systems development, with conceptual modelling being considered the key to achieving data integration.{{Cite web|url=

单词	External schema
释义	External schema 英语百科 Three-schema approach The three-schema approach, or three-schema concept, in software engineering, is an approach to building information systems and systems information management that originated in the 1970s. It proposes three different views in systems development, with conceptual modelling being considered the key to achieving data integration.{{Cite web\|url=
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External schema

Three-schema approach