I'm not sure I really consider SQL a programming language though. Certainly doesn't seem fair to compare it to anything turing complete (at least, unless you're going to lump in extensions such as PL/SQL or T-SQL.
Doesn't detract from the advice to learn it though. Picking up books on Perl and C as a teenager always left me feeling like I was missing something key that'd make programming more accessible, and I learned FAR later that what that was was an appreciation for making better use of structured data. In lieu of either larger data structures or microcontrollers, everything I looked at felt like a much more complicated and slightly more capable calculator; the access to large relational data models is really where the super powers of turing complete languages clicked.
Doesn't detract from the advice to learn it though. Picking up books on Perl and C as a teenager always left me feeling like I was missing something key that'd make programming more accessible, and I learned FAR later that what that was was an appreciation for making better use of structured data. In lieu of either larger data structures or microcontrollers, everything I looked at felt like a much more complicated and slightly more capable calculator; the access to large relational data models is really where the super powers of turing complete languages clicked.