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Mike Champion scripsit: > The key differentiator was that CODASYL ultimately > relied on "pointers" (which I'm pretty sure are functionally much like > hyperlinks, at least by analogy) to relate bits of information that did > not fit into a hierarchy, Actually, the CODASYL model was about multi-hierarchies, with none preferred. Here's how you'd do the CODASYL model on a relational DBMS, which is historically backward, but a lot more people understand RDBMSes. Data is kept in objects like relational tables, except that the primary key is always a generated unique ID. (Implementationally, this was an address.) Then there would be linkage tables, potentially one per pair of tables, with the fields <primary key 1>, <primary key 2>, <sort order>. (This was implemented as a linked list of primary-key-2s starting from the record labeled by primary-key-1.) All navigation must be done through these links. -- What is the sound of Perl? Is it not the John Cowan sound of a [Ww]all that people have stopped jcowan@r... banging their head against? --Larry http://www.ccil.org/~cowan
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