HP Integrity NonStop J-Series - Manual (Page 104)

CREATING AND RUNNING A MULTIFILE APPLICATION
Associating and Linking Boxes
If you use the second form of the LINK OPTIONAL parameter, you
enter the name of the parent box, the name of the child box, and
the common name of the join fields from both boxes, for example:
SET APPL TREE (01 region
02 branch
LINK region TO OPTIONAL branch
VIA regnum)
In this case:
• "region" is the parent box.
• "branch" is the child box.
• "regnum" is the join field in both parent and child records.
Effect of the Tree Structure on a Generated Application
When you build a tree structure for your application, that
structure affects the following aspects of a generated
application:
• The screen displayed by the application, as follows:
--A field from the box at the first level always appears as
the field on the screen.
--The join field of a parent box always appears on the
screen immediately before any child box (or boxes).
--A join field of a child box does not appear on the terminal
screen.
• The records that can be read and inserted for each box: The
organization of the tree structure determines the access path
that the generated application follows to read and insert
records.
The following paragraphs describe two sample tree structures and
discuss how these tree structures affect the preceding aspects of
their respective applications.
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