Pathmaker Programming Guide

Creating a DB Requester Application
Pathmaker Application Development Overview
3–22 067868 Tandem Computers Incorporated
Note If a READ APPROXIMATE is requested for an Enscribe file that has a multifield key, all values entered in
those key fields will be used to determine which record to read first. For example, if a file has a three-field
key and the end user enters 3, 6, 2 on the screen in the corresponding key fields, the application uses all
those values to determine the first record to return (“3, 7, 0”, for example).
Single-File and Multifile
DB Requesters
You can create a DB requester application that accesses:
Only one table or file (a single-file DB requester)
Multiple related tables or files (a multifile DB requester)
You cannot, however, mix NonStop SQL tables and Enscribe files in a single DB
requester.
Before a DB requester that accesses NonStop SQL tables can be created, all tables and
views of tables used must be registered using the Table Registration screen. (Refer to
“Registering NonStop SQL Tables” in Section 2, for details.)
Note Although the following information about single-file and multifile DB requesters applies to both Enscribe
and NonStop SQL applications, this text is written using Enscribe terminology unless otherwise specified.
Single-File DB Requesters
Single-file DB requester applications are the simplest type of application that can be
created using the Pathmaker product. A single-file DB requester application can be
used to add, delete, insert, or update one or more records from a single file. Multiple
records from a single file are referred to as repetitions. A DB requester application,
based on a single-file DB requester, displays a screen to the end user that contains a
title and function key prompts and, for each repetition, a set of data fields from that
file and labels that identify these data fields.
The end user of a single-file DB requester that displays several repetitions of a record
uses the cursor to identify to which repetition an operation applies.
Figure 3-8 provides an example of a screen from a single-file DB requester application
used to maintain information in one file (on one repetition at a time) in a test database.
Employee Number is the primary key of this file. Employee Name is an alternate key.