Dictionary/3000 Reference Manual (32244-90001)

338 AppendixD
How HP INFORM Links Files to Generate Reports
Default File Access
Assume the following database:
Suppose we wish to create a group called BOOKS OUT. The purpose of the BOOKS OUT
group is to generate reports about books that are checked out of the library. The group
consists of the data elements:
title
author
call-no
borrower
phone
Since the purpose of the BOOKS OUT group is to report on books that are checked out, it
makes sense to access the detail set CATALOG as the first file; since CATALOG has only
one entry for every book checked out, there will be at least one line of the report for each
book that is checked out of the library. That is, CATALOG contains the appropriate subset
of data which is desired for reports which will be generated from the BOOKS OUT group.
BOOK, TITLE, and CALL-NO, on the other hand, have one entry for each book in the
library; if one of these files is the first file accessed, there will be at least one line of the
report for every book in the library. Accessing BORROWER or AUTHOR as the first file
would also not be satisfactory, since BORROWER has one entry for each person registered
to check out books from the library and AUTHOR has one entry for each author.
(SUBJECT and LOCATION are not considered since they do not contain any elements
from the group.)
To make CATALOG the driving file, we need to specify the file name CATALOG in
response to the FILE prompt and a link value of 1 in response to the VALUE AS A LINK
*title
*author
*subject
*call-no
pub-date
publisher
*call-no
*borrower
bor-date
*branch
CALL-NO
*call-no
SUBJECT
*subject
AUTHOR
*author
TITLE
*title
LOCATION
*branch
city
BORROWER
*borrower
phone
CATALOG
BOOK
*search item