I know the answer, and SQL, but some of my colleagues (AS400/Synon/RPG programmers/code grinders all) can't see the point. Why should they bother spending time learning SQL when Query/400, a fine tool for running ad-hoc queries on the AS400 will do enough? If Query/400 isn't man enough for the job then they can always write a program in RPG or Synon:2e/Cool:2e/Advantage:2e/Fusion:2e.
They view SQL as a tarted up version of Query/400 without the comfortable, familiar, front end. Do they know how powerful SQL is? Do they know that it is portable? That it can be embedded in almost any language? That if you know SQL you can set up a database almost anywhere (bearing in mind that you might have to learn some local stuff)? Do they see it as a database language in its own right? Have they been spoiled by the iSeries native database (which is, to be fair, not user unfriendly and bombproof). Or are they in denial?
So, why should they learn SQL? Your opinion, as usual, will be welcomed.
Stone soup, Boiled Frogs and Broken Windows – I'll start the ball rolling by suggesting that they read
The Pragmatic Programmer.