Pathmaker Programming Guide

Updating Rows

How to Operate a DB Requester Application

067868 Tandem Computers Incorporated B–15

If the application displays this prompt, the end user must enter either the character Y

(to continue) or the character N (to stop), and then press F1. If a Y is entered, the

application continues the UPDATE BOX operation beginning with the record that

directly follows the record in error. If an N is entered, the application stops the

UPDATE BOX operation. In this case, the application has already updated any

records that appear above the record in error. The end user can, however, request an

UNDO operation at this point and return the database to its previous condition.

For applications that access NonStop SQL tables, if an error is encountered during an

UPDATE BOX operation, all columns in error are highlighted and the application

displays the message associated with the first column in error in the message area.

The application will update all rows that are error free.

The effects of an UPDATE BOX operation can be reversed by requesting an UNDO

(shifted F13) operation immediately after the UPDATE BOX operation.

UPDATE Considerations

for Applications With

Several Boxes

When the value in the join column of a parent row needs to be changed, the end user

will usually want to change the join columns of the associated child rows, too. The

procedure for updating a join column is as follows:

1. Request a read operation to retrieve the parent row.

2. Request a read operation to retrieve the nested row(s).

3. Delete the nested row(s).

4. Repeat Steps 2 and 3 until the application does not return a row as a result of the

read operation.

5. Change the necessary columns of the parent row.

6. Press F14 to update the row in the parent box.

7. Replace the nested row(s) by requesting the appropriate insert operations for the

nested box.

If many nested rows need to be deleted and replaced, the end user might request two

single-table applications that can be used to change the join column values of these

rows.