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Re: In an RDBMS, what does "Data" mean?

From: Bill H <wphaskett_at_THISISMUNGEDatt.net>
Date: Mon, 14 Jun 2004 12:12:28 -0700
Message-ID: <40cdf918$1_7@corp.newsgroups.com>

"Eric Kaun" <ekaun_at_yahoo.com> wrote in message news:wekzc.25516$Dh6.9215_at_newssvr31.news.prodigy.com...
>
> "Bill H" <wphaskett_at_THISISMUNGEDatt.net> wrote in message...
> >
> > The field definitions are where the descriptions of the field are kept.
> > Any such relationships that exist (such as field#s 9 & 10 below) are
> > also kept in the field definition. Again, it is not the database that
> > enforces these rules, it's the application. You might see the
> > following:
> >
> > 009 1010]1020]1050]1090
> > 010 2500]32500]17525]15
> > 011 9]12]33]34]35]36]37]38]39
> >
> > in a customer record where:
> >
> > 009 - The G/L acct#s of recurring monthly billings (such as support
fees).
> > 010 - The amount of each G/L acct#s recurring billing amount.
> > 010 - The unpaid invoices still associated with this customer.
> >
> > This is very usual and a single disk read gets the salient properties of
> > the customer record. The dictionary for the G/L acct#s may be defined
> > as being the controlling field with a relationship to field# 10 while
> > field# 10 is dependent on field# 9.

[snipped]

>
> While I see many examples like the above, can you give us an example of
how
> the dictionary defines those?

Here's the field definition for the Accounts and Amounts:

    accounts
001 A
002 9
003 ACCT
004 C;10
005
006
007
008
009 L
010 5
011
012
013
014
015
016
017 The G/L acct#s associated with this invoice (controls field# 10)

    amounts
001 A
002 10
003 ACCT/AMTS
004 D;9
005
006
007 MR2,M
008
009 RN
010 13
011
012
013
014
015
016
017 The amounts associated with each G/L acct# in field# 9.

Field# 004 in the above definitions defines the controlling and dependent fields. The above structure may be different in different mvDbms products. Anyway, these definitions are data just like other data and reside in the database.

> What language do you use to define the dictionary? Is it user-accessible?
>
> - erk

As you can see, the definitions are just data. They describe the data the definitions have a pre-defined structure (the dbms defines this structure). One builds a dictionary through various tools (line editor, screen editor, GUI editor, GUI dictionary editor, etc). The query language uses the field definitions so I could:

LIST APINVOICES ACCOUNTS AMOUNTS and get the following output:

apopen.... ACCT. ACCT/AMTS....

                 *
555*1011   5070          6.73
340*VR3-2  5170      1,012.61-
           3370      1,963.84-
           5170          0.00
           3370          0.00
9999*3907  5000        300.00
555*1018   5070         29.53
340*VR11-1 5170        999.22-
           3370      1,977.23-
           5170          0.00
           3370          0.00

So the data is accessible by users or developers and the field definitions can be accessed in the same way (since they're just data too) using the query language:

LIST DICT APOPEN 'ACCOUNTS' 'AMOUNTS' D/CODE A/AMC S/NAME  V/STRUC V/TYP V/MAX DICT APOPEN code A/AMC S/NAME.............. c/d struc. TP MAX

ACCTS       A        9 ACCT                 C;10       L  5
AMTS        A       10 ACCT/AMTS            D;9        RN 13

[405] 2 items listed out of 2 items.

Hope this helps.

Bill

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