Good morning Hugh;
I have read many references defining a relational database. It may be nothing more than an academic exercise but there are a number of camps concerning this topic. Sometimes you will hear the term “pseudo RDBMS” in reference to the dbf format. If you are a purest you have one viewpoint and if you are “impure” you have an entirely different opinion of the world and everything in it. For the ten years we have known each other I am sure what we both think about “pure thoughts and dogma”!
The “Indexed Sequential Access Method” (ISAM) was developed by IBM and predates the relational database. The ISAM method uses an index tag for each desired field. Two files are used, one for data and one for an index. FoxPro falls into this category.
I remember reading an article a few years ago stating that “FoxPro dbf’s are 90% compliant with the relational database model”. Again if you are a purest you will reference that 10% value as your validation against the dbf format being “a true relational database model”.
Now if you wish you can approach E.F. Codd’s work on the relational database model. In the relational model all data, structure and rules are contained within the table. Codd defined his twelve principles of relational databases in 1974.
Tom
Reference:
1. E. F. Codd, "The Relational Approach to Data Base Management: An Overview", Third Annual Texas Conference on Computing Systems (1974).
Codd's 12 principles of relational databases.
2. E. F. Codd, The Relational Model for Database Management (Addison-Wesley Publishing Company, 1990), 538 pages; clothbound; ISBN 0-201-14192-2.
Codd, the father of relational systems, updated his famous manifesto for the relational model in 1990. It now demands conformance to 333 principles for any database system to be labeled "relational".
Both of these books sit on a shelf of one of my bookcases. Somehow I think Codd will publish another book in the coming years that will increase the requirements even further.
>Hi Alejandro,
>
>Please educate me on this topic. I'm confused. Specifically what does Visual FoxPro have (or not have) that precludes it from being a relational database management system (RDBMS) in your opinion?
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>I did a little bit of Googling and came up with a few definitions all of which seem to fit Visual FoxPro:
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http://searchdatabase.techtarget.com/sDefinition/0,,sid13_gci212885,00.html>
>Here's another one that seems to fit:
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http://www.webopedia.com/TERM/R/RDBMS.html>
http://www.webopedia.com/TERM/D/database_management_system_DBMS.html>
>Oh, here's another one that fits:
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http://www.sf-systems.com/technology/tech080102.shtml>
>and this one too:
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http://coral.lili.uni-bielefeld.de/EAGLES/WP5/termdeliv97/node38.html>
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>
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>Hugh
