Customizing Database Calls

Restriction: This topic applies only when the AppMaster Builder AddPack has been installed, and applies only to Windows platforms.

You can execute custom logic at any of several Express-provided events that occur during database call processing:

Event	Occurrence
Before DB Access	Before a non-loop database call executes
Before Loop	Before a loop database call executes
Normal Status	After processing records, and before moving them to the window or screen
Normal-X Status	For looped records only. After Normal Status executes, and before moving records to the window or screen
Error Status	After the database call returns an Error status flag
Exception Status	After the database call returns an Exception status flag
After DB Access	After a non-loop database call executes
After Loop	After a loop database call executes

The Normal Status and Normal-X Status events enable you to add custom logic before looped records map to your screen. Use these events when you want to map only some of the records that a loop obtains. In your custom code, write conditional logic to determine which records to map. Online Express provides a flag, OK-TO-PROCEED, that you set to True to map and process the record, or False to bypass mapping and processing. You can ignore the flag if you do not use this event; the flag is set to True by default.

The following example illustrates both events. Suppose that you must map the records that show annual sales of $100,000 or more in the Northwest region, and calculate and map the grand total of those records.

First, you define a loop call and qualify it to obtain the records of $100,000 or more.
Then, you tailor the loop call with two paragraphs.
- The first paragraph (at the Normal-X Status event) checks the records obtained by the loop and process records of the Northwest region only.
- The second paragraph (at the Normal Status event) calculates the grand total of those records, and maps the total to the screen.

Using the Normal Status Events - Generated Code

DB-PROCESS REC SALES-RECORD
... WHERE ANNUAL-SALES-TOTAL > 99999
    PERFORM CHECK-BEFORE-MAPPING-PARA
    IF OK-TO-PROCEED
        ADD 1 TO CTR
        PERFORM RECORD-STOREKEY-PARA
        PERFORM CALC-AND-MAP-PARA
        MOVE REC-TO-SCREEN-LB1
     .
     .
     .
CHECK-BEFORE-MAPPING-PARA
    TRUE OK-TO-PROCEED
    IF SALES-REGION NOT = NORTHWEST
        FALSE OK-TO-PROCEED

CALC-AND-MAP-PARA
    calculation and mapping routine for grand total

In the example code:

The CHECK-BEFORE-MAPPING-PARA paragraph executes at the Normal Status event. Express generates the paragraph PERFORM statement.
The CALC-AND-MAP-PARA paragraph executes at the Normal-X Status event. Express generates the paragraph PERFORM statement.
Online Express generates all code subordinate to the DB-PROCESS call.