March 2022
Intermediate to advanced
682 pages
22h 58m
English
Content preview from Databases Illuminated, 4th Edition
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4.1 Advantages of the Relational Model
The relational model has replaced earlier hierarchical and network database systems. The earlier models were based on file systems, and the databases created using them required that the application programs contain details about the layout of data in the database. For this reason, whenever the database was reorganized, the applications had to be rewritten. There was no physical data independence. The relational model removed such details from the applications, providing a logical view and creating true data independence for the first time. Section 1.6 describes the history of this evolution.
The relational model is based on the mathematical notion of a relation. Codd and others extended this notion to ...
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