Chapter Notes
The classic discussion of the conceptual, internal, and external schemas of an information system is given in van Griethuysen (ed. 1982). Some people who worked on this ISO standard also worked on the FRISCO Report (Falkenberg et al. 1998). Along with many other authors (e.g., Elmasri and Navathe 1994), we consider the relational model of data to be a logical model rather than a conceptual model, mainly because it is too distant from natural language. From this viewpoint, a relational schema represents the logical portion of an internal schema (omitting details specific to the chosen DBMS, and storage and access details such as indexes). Codd (1990, pp. 33-34) proposes an alternative interpretation of the three-level architecture, ...
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