SQL Primer
From MidrangeWiki
More info from main SQL page.
If your security will let you do this, get to a 400 command line and key in STRSQL and enter, which brings up something that LOOKS like a command line. Then key in SELECT and do F4 ... which brings up various lines where you can get at directory of libraries on your 400 ... pick 1 or more ... then pick what files you want to do some SQL access against ... then pick what fields to include in your SQL on the fly ... when this contributor (Al Mac) learns how to do NEW pages, I may attempt some kind of tutorial introduction to SQL because I do not have a single SQL manual, just a bunch of articles, that I study assiduously.