As I've mentioned previously, our team spends a lot of time and energy teaching the virtues of DB2 for i and guiding folks on the notion of data centric programming via SQL. To that end, we have formal courses that serve to educate, enable and energize the IBM i development community. One such course is the newly updated and enhanced "IBM DB2 for i Advanced SQL Programming".
To get an idea of what the course covers, including topics and level of detail, please take a look at the short video recently produced...
English version by Kent Milligan
Spanish version by Hernando Bedoya
If you are interested in this particular course or anything else related to SQL and getting the most out of DB2 for i, please contact me.