Chapter 7. Virtual Tables
TABLES ARE NOT anything like files. Traditional procedural programmers have to make a “leap of abstraction (faith)” in SQL that does not exist in their model of data. Imagine that you are working with nothing but punch cards and magnetic tapes. Every step in your processing will result in the creation of a physical file. A master tape file was merged with punch card or tape transaction files to produce a new master file. Most of the machine time was spent doing sorts and merges on such files. Electronic data processing (EDP, as we called it back in those days) depended on sequential access to data so that computations could be done in relatively small primary storage devices. You could not put an entire file into primary ...
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