Simple Inquiry Subfile Pattern

Learning Objective

By the end of this lesson, you will be able to read a complete, simple RPGLE program that clears, loads, and displays a load-all subfile showing a list of records.

Simple Explanation

This lesson brings together everything covered so far in this lesson group: the subfile record format and control record format pair, SFLCLR, SFLDSP, and SFLDSPCTL, and the load-all strategy. Here is a small, complete example listing a customer's orders, using the ORDSFL subfile record format and ORDCTL control record format introduced in earlier lessons:

**free
ctl-opt dftactgrp(*no);

dcl-f ORDLISTD workstn;

dcl-s i int(10);
dcl-s ordNbr packed(6:0);

// Step 1: Clear the subfile before loading it
*in30 = *on;
*in40 = *off;
write ORDCTL;

// Step 2: Load records into the subfile
for i = 1 to 5;
  ordNbr = 1000 + i;
  write ORDSFL;
endfor;

// Step 3: Display the loaded subfile
*in30 = *off;
*in40 = *on;
*in41 = *on;
exfmt ORDCTL;

*inlr = *on;

Reading this step by step: *in30, the SFLCLR indicator, is turned on and *in40, the SFLDSP indicator, is turned off, then write ORDCTL performs the clear without showing anything meaningful. The program then loops, writing five order records into the ORDSFL subfile record format, one at a time. Finally, *in30 is turned back off, and *in40 and *in41, the SFLDSP and SFLDSPCTL indicators, are turned on before exfmt ORDCTL actually shows the control record format, along with the five loaded orders, to the user.

Why It Matters

This is the complete, basic shape behind a large number of real IBM i list screens: clear, load, display. Seeing every piece from earlier lessons in this group working together in one small, complete example helps each individual concept, the subfile and control record format pair, the clear/load/display indicators, and load-all loading, click into a working whole.

Practical Example

Imagine a customer service representative pulling up an order history screen. Behind the scenes, this program clears any previous subfile contents, loads that customer's orders one at a time in a loop, and then displays the control record format, showing the representative every loaded order at once, ready to scroll through.

This is a simplified, illustrative example rather than a specific real program, and a real version would load actual order records from stored data rather than generating fixed order numbers in a loop, but it reflects the genuine, everyday shape of a simple load-all subfile program.

Common Confusions

"Why is exfmt used only at the end, and write used for the clear step and each loaded record?" write sends something to the screen without waiting for a response, as covered in the READ, WRITE, EXFMT, and Screen Flow lesson, which is exactly what is needed for the clear step and for loading each record; none of those steps should pause and wait for the user. exfmt is used only at the very end, once everything is ready, to actually show the completed list and wait for the user's response.

"Does the order of turning indicators on and off matter?" Yes. Clearing must happen with SFLDSP off, so the clear operation completes cleanly, before switching back to loading and then finally turning SFLDSP and SFLDSPCTL on for the actual display step. Reversing this order would show an incomplete or already-cleared subfile.

"Does this program load real data from a physical file?" No, not in this simplified version. The order numbers are generated in a simple loop to keep the focus on the subfile pattern itself. A real version would replace that loop with actual reads against stored order data, building on the Db2 for i lessons covered earlier in this path.

Quick Recap

• A basic load-all subfile program follows a clear, load, display sequence, using write for the clear step and each loaded record, and exfmt only for the final display.
• Clearing happens with SFLCLR on and SFLDSP off; displaying happens with SFLCLR off and SFLDSP/SFLDSPCTL on.
• This pattern combines the subfile and control record format pair, clear/load/display indicators, and load-all loading from earlier lessons into one complete, working example.
• A real version of this program would load actual stored data instead of generating fixed example values.

Try Asking the AI Tutor

Use the AI Tutor to ask follow-up questions about this lesson. For example, try asking:

• "What would need to change in this program to load real order data instead of generated values?"
• "What would happen if I forgot to turn SFLDSP back on before the final exfmt call?"