HP Integrity NonStop J-Series - Manual (Page 98)

CREATING AND RUNNING A MULTIFILE APPLICATION
Associating and Linking Boxes
2. For a box at any level except the first, a join field must
exist that links that box to a parent box at the next lower
level of the tree structure.
3. If you link two or more boxes to the same parent box, these
boxes must reside at the same level of the tree structure.
The level at which a box resides in the tree structure affects
the appearance of the screen displayed by the application as
follows:
• A field from the box at the first level of the tree must
appear as the first field on the screen.
• For each subsequent level, a field from a box at that level
must appear before any fields from boxes at higher levels.
Before you determine the levels at which your boxes are to
reside, consider the purpose for which you are generating the
application, the possible links that you can establish between
boxes, and the logical relationship between these boxes.
If your application uses only two boxes, you can identify either
box as residing at the first level of the tree structure.
If your application uses three or more boxes, the process of
determining appropriate levels becomes more complicated.
Suppose, for example, that you want to generate an application
that uses three boxes: "employ-box," "depends-box," and
"insure-box." Assume that these boxes represent the following
information:
• "Employ-box" represents general information about employees.
• "Depends-box" represents information about the dependents of
these employees.
• "Insure-box" represents information about each employee's
insurance coverage. This information also indicates whether
dependents are covered by the employee's insurance.
Now suppose that each of these boxes has a field that represents
an employee identification number. Depending on the purpose for
which you are generating this application, you could build a
variety of tree structures with a variety of links. Figure 5-7
illustrates the various tree structures which you could build for
these boxes.
5-14