What Can I Select When I Group?
Dear highly esteemed professional colleague:

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. READ MORE >

To Shift or Not to Shift: That Is in the Fourth Parameter
by Ted Holt

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?. READ MORE >