CodeSOD: Do you like this page? Check [Yes] or [No]

In the far-off era of the late-90s, Jens worked for a small software shop that built tools for enterprise customers. It was a small shop, and most of the projects were fairly small- usually enough for one developer to see through to completion.

A co-worker built a VB4 (the latest version available) tool that interfaced with an Oracle database. That co-worker quit, and that meant this tool was Jens's job. The fact that Jens had never touched Visual Basic before meant nothing.

With the original developer gone, Jens had to go back to the customer for some knowledge transfer. "Walk me through how you use the application?"

"The main thing we do is print reports," the user said. They navigated through a few screens worth of menus to the report, and got a preview of it. It was a simple report with five records displayed on each page. The user hit "Print", and then a dialog box appeared: "Print Page 1? [Yes] [No]". The user clicked "Yes". "Print Page 2? [Yes] [No]". The user started clicking "no", since the demo had been done and there was no reason to burn through a bunch of printer paper.

"Wait, is this how this works?" Jens asked, not believing his eyes.

"Yes, it's great because we can decide which pages we want to print," the user said.

"Print Page 57? [Yes] [No]".

With each page, the dialog box took longer and longer to appear, the program apparently bogging down.

Now, the code is long lost, and Jens quickly forgot everything they learned about VB4 once this project was over (fair), so instead of a pure code sample, we have here a little pseudocode to demonstrate the flow:

for k = 1 to runQuery("SELECT MAX(PAGENO) FROM ReportTable WHERE ReportNumber = :?", iRptNmbr)dataset = runQuery("SELECT * FROM ReportTable WHERE ReportNumber = :?", iRptNmbr)for i = 0 to dataset.count - 1 if dataset.pageNo = k then useRecord(dataset)dataset.MoveNext endnextif MsgBox("Do you want to print page k?", vbYesNo) = vbYes thenprint(records)endnext

"Print Page 128? [Yes] [No]"

The core thrust is that we query the number of pages each time we run the loop. Then we get all of the rows for the report, and check each row to see if they're supposed to be on the page we're printing. If they are, useRecord stages them for printing. Once they're staged, we ask the user if they should be printed.

"Why doesn't it just give you a page selector, like Word does?" Jens asked.

"The last guy said that wasn't possible."

"Print Page 170? [Yes] [No]"

Jens, ignorant of VB, worried that he stepped on a land-mine and had just promised the customer something the tool didn't support. He walked the statement back and said, "I'll look into it, to see if we can't make it better."

It wasn't hard for Jens to make it better: not re-running the query for each page and not iterating across the rows of previous pages on every page boosted performance.

"Print Page 201? [Yes] [No]"

Adding a word-processor-style page selector wasn't much harder. If not for that change, that poor user might be clicking "No" to this very day.

"Print Page 215? [Yes] [No]"

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