Category Software Related Stories Handling Data with SQL -- 11/17/98 Next: Relational Model Basics

Continued from What is SQL?

Simply stated, a relational database system is based on the relational model for managing data.

The relational model was first introduced in a paper published in 1970 by Dr. E. F. Codd. It provided a mathematical basis for structuring, manipulating, and controlling data, and it abstracted data from any physical implementation. Prior to that time, database users had to know how records were physically linked in order to access them. When the physical structure of a database was changed (for performance reasons, for example), programmers had to rewrite their applications, even if the logical structure remained the same. In the relational model, data is separated from application programs. In fact, the model said nothing whatsoever about how data should be stored or accessed. It dealt exclusively with how data was seen from the user's point of view. The relational model significantly changed the way people thought about managing data. It transformed database technology from an art into a science and revolutionized the industry.

Next: Relational Model Basics

Published as PC Tech Feature in the 11/3/98 issue of PC Magazine.

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