Pathmaker Programming Guide

Reading Rows
How to Operate a DB Requester Application
B–4 067868 Tandem Computers Incorporated
READ APPROXIMATE Operation for a Nested Box
For a nested box, a READ APPROXIMATE operation can be performed only if a key
column appears in the box. (If a key column does not appear and a READ
APPROXIMATE operation is requested, the application performs a READ FIRST
operation.) If a key column appears, the end user must do the following to request a
READ APPROXIMATE operation:
1. Read or insert a row into the parent box.
2. Enter a value in the key column of the nested box.
3. Press F6.
READ EXACT (F7) To retrieve the first row(s) with a key column value that exactly matches the one
entered on the screen, the end user must request a READ EXACT operation. If a value
for the primary key column is entered, the application returns the single existing row.
If a value is entered for an index column that has duplicate values, the application
retrieves the first row(s) that have that index value.
If a key consists of multiple columns, the end user must enter a value for each of those
columns prior to requesting a READ EXACT. (This is also true for multiple field keys
for Enscribe files.)
Consider, for example, the following Enscribe group key field:
+ DEPT
REGNUM __
BRANCHNUM __
To request a READ EXACT on DEPT, the end user must first enter a value in both
REGNUM and BRANCHNUM. If a 1 is entered in REGNUM with no value entered in
BRANCHNUM, the application will not find a record unless REGNUM = 1 and
BRANCHNUM = 0.
READ EXACT Operation for an Outermost Box
To request a READ EXACT operation, the end user must do the following:
1. Enter the entire key value in the key column(s) on the screen.
2. Press F7.