It’s not uncommon for someone to ask me for help with error SQL0122, which involves SQL commands that use the GROUP BY clause to produce summary figures. Since I see this error over and over and over, I thought it would be good to explain how summary queries work. The standard rule I hear is that the SELECT clause of summary queries can list aggregate fields (those in the GROUP BY clause), expressions that are in the GROUP BY clause, and column functions, such as COUNT, SUM, and AVG. That’s close, but slightly inaccurate.

A reader who contacted me recently

RPG’s %REPLACE function is marvelous. When I think of all those array-manipulation calcs I wrote in my System/34 and System/36 days, I could cry. Anyway, to use %REPLACE effectively, it is good to ask oneself a simple question: In the event that the replacement string and the string of characters that is being replaced are not the same length, do I, or do I not, want the characters that follow the replacement to shift?

This is the same question SEU asks on the Find/Change Options panel. Informing SEU of your desire is an almost effortless matter of typing a Y

Part 1

Critical storage errors can occur whenever i5 hard drive usage passes 90 percent of available storage space. Above 90 percent, system performance starts to degrade. When storage usage breaches 95 percent, the system can become unstable and turn itself off or spontaneously reboot. While you can’t predict when critical storage errors will occur, there are several things you can do to detect and cleanup storage problems before they crash your system.

What’s the Disk Facts, Jack?

This week and next week, I’ll deal with the issues involved in monitoring and correcting critical storage errors or storage overflow conditions.

We are at security level 30 in i5/OS and we have been told by our auditors that we need to move to security level 40. What are some of the benefits that we will see going to level 40, and is it as simple as changing the QSECURITY system value? Some of what I read tells me I have to start journaling in order to see if I can run at level 40, but then it says I can go to level 40 just by changing the system value. What is the real answer here?

–Bob

Besides all of the