On Mon, Sep 3, 2012 at 10:01 AM, John Weller <[email protected]> wrote:
> I worked on a system many years ago using FPW 2.6 which would have benefited > from this approach! They wanted to store information about the company in a > table for reference so had a table with a single row and many columns. > Unfortunately they needed to store more than the 256 field limit so had to > have 2 tables Company1 and Company2 so we had to remember where each item > was stored - not good! And I worked on a system that went to the opposite extreme: Single fields were stored in their own rows, in one of four tables: strings, numbers, dates, booleans. The (multiple) keys were: System c(2) Subsystem c(4) Module c(4) Screen c(3) serial c(2) And all of the codes for the keys were stored, yup, in the tables. So, it had a built-in self-referential data dictionary. While it sounds unwieldy, the originator (not me!) had designed a series of functions so that lookups were very efficient. There was a LOT of disk I/O for a complex screen, but screen drawing on PS/2 50Z's were never that fast ;) And this was FP 2.x, so there were no transactions. A mid-update power failure or disk error would wreak havoc on data integrity. So, a customer address data record would consist of a series of lookups for Customer Name, Address1, Address2, etc. Adding a field just meant adding a new record to the data dictionary; no file locks, no header locks. You had to gracefully deal with NULLish values in those records until you backfilled, if needed, of course, but the system had remarkable flexibility. Years later I worked on one of the OOP databases and was surprised to see a very similar design. I think it was extreme as far as RDBMSes was concerned, but it worked. -- Ted Roche Ted Roche & Associates, LLC http://www.tedroche.com _______________________________________________ Post Messages to: [email protected] Subscription Maintenance: http://leafe.com/mailman/listinfo/profox OT-free version of this list: http://leafe.com/mailman/listinfo/profoxtech Searchable Archive: http://leafe.com/archives/search/profox This message: http://leafe.com/archives/byMID/profox/cacw6n4sft1nxdn+i_ji77gqndgs5zgj+oyikb+npugmqrrf...@mail.gmail.com ** All postings, unless explicitly stated otherwise, are the opinions of the author, and do not constitute legal or medical advice. This statement is added to the messages for those lawyers who are too stupid to see the obvious.
