We could wallpaper all 500 rooms of the computer science building at MIT with different SQL tutorials from various publishers. Yet when it came time to sit down with our students and teach them this material, we couldn’t bear to use any of the commercial texts.
The CS department at MIT doesn’t offer a course in SQL (or in any other computer language per se for that matter). But lots of universities do and therefore you can choose from many textbooks designed to teach SQL to 20-year-old CS majors. Perfect, eh? Not for us. Part of the problem is that universities try to give students what they deem to be eternal knowledge. So rather than focus on the relational model and SQL, the overwhelmingly dominant system for the past 20 years, introductory database textbooks spend several chapters talking about database management systems that were used in the 1960s.