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                    *          DB/C Newsletter          *
                    *           December 1996           *
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                               Editor's Notes

     Beta test versions of both FSS 1.0 and DB/C 9.1 are now available.
This software may be retrieved from the Subject, Wills & Company ftp
server, ftp.swc.com, for your testing and inspection.  The FSS 1.0
beta test software is in /pub/misc/fsstest.  The DB/C 9.1 beta test
software is in /pub/misc/dbc91tst.  Read the README.TXT files in each
of these directories to find what operating environments are supported,
the current status of the beta test software, and what to download.
Both of these directories can be accessed using anonymous login.

     This month's article contains information about using FSS.  Several
common errors and misunderstandings have occurred during the alpha and
beta testing of FSS.  Hopefully, the information in this article will
help you to avoid these same mistakes.

     LAST NOTICE:  The new area code of the phone numbers of Subject,
Wills and Company is 630.  The old area code no longer works.

                                                            don.wills@swc.com


                               Using FSS 1.0

     The most common misunderstanding about the DBD file is how to
represent numbers stored in a DB/C file.  SQL does not count the period
character that separates the integral part of a number from the fractional
part.  Additionally, the first number in an SQL numeric specification is
the total number of digits in the number.  Here are some examples:

      DB/C specification        SQL (and DBD file) specification
      ------------------        --------------------------------
          FORM 7                        NUMERIC (7)
          FORM 7.2                      NUMERIC (9,2)
          FORM 0.2                      NUMERIC (2,2)

Note that in FSS, NUMERIC and DECIMAL have the same meaning.  In Standard
SQL, NUMERIC and DECIMAL are allowed to have somewhat different meanings.

     The POSITION parameter is an important DBD file parameter that was
omitted from the FSS documentation that is dated before December 2.  This
parameter specifies the position of a column within each record of a file.
This is useful for skipping filler characters, for skipping over columns
that should not be visible to the user, and for reordering the view of the
columns that the user sees.

     The current beta test version of the software does not allow a record
in the file that is longer than the highest character position defined in
a column.  This will be fixed before FSS 1.0 is released.

     The READONLY parameter was added as a result of alpha tester feedback.
This parameter specifies that an entire table may not be modified by the
user.

     An issue that was brought up is the use of files that contain more
than a single type of record.  Files that contain variable length records
is a related issue.  SQL was not designed for either of these situations.
Therefore, FSS does not handle them.  Note that the COMPRESSED parameter
used in conjunction a TABLE implies that the file may not be updated in
place because it is a DB/C compressed type file.  In this case, updates
are actually implemented by deleting a record and rewriting the updated
record at the end of the file.

     One person asked about using arrays of columns.  Again, the design of
SQL precludes the use of arrays, so FSS does not support them.

     A couple of people have bumped into file location and path specification
problems.  Note that using the FSS.CFG file is optional.  If it is used, it
must be either in the current directory of the application or it must be in
a directory in the system PATH environment variable.  If it is not in either
of those locations, FSS assumes you are not using an FSS.CFG file.  Several
different kinds of errors can occur in this situation, including a table
not found error on the first select statement.

     In FSS 1.0, the name and password that are specified in the connection
to the FSS database are ignored.

     If you have any more tips for using FSS, let us know so we can share
them with other FSS users.

     

                             DB/C Class Schedule

        Class                        Date                    Location
DB/C 9 Fundamentals           January 21-23, 1997          Oak Brook, IL
DB/C 9 Advanced Features      January 28-30, 1997          Oak Brook, IL

For information, contact Judi Tamkevic at:
     voice  630.572.0240
     fax    630.572.0390
     email  dbc@swc.com