And that confusion relates to copyright issues, and name changes because of them.
The first version, from IBM circa 1974, was named Structured English QUEry Language (“SEQUEL”). But IBM discovered that SEQUEL was already copyrighted in the UK by an aircraft company. So when they came out with the next version, and extensively changed product, they renamed it to Structured Query Language (“SQL”) and said it was to be prounced as the letters {“ess queue el”). Edgar Codd, inventor of the relational database, encouraged this renaming – he wanted a major break from the previous version (named SEQUEL) because that was a bad implementation – it violated several of the fundamental ‘rules’ of relational databases. But many of the experienced, expert users continued to pronounce it as sequel, even though it’s written SQL.
When other companies (like Oracle) came out with their versions of relational databases, they used SQL as the name for their version of the access language. Because they felt that acronym was safe from copyright infringement claims by IBM.
The ess queue el pronunciation is still the correct one, officially, and so listed in the ANSI Standard. But lots of people pronounce it sequel (Zipf’s Law in action).
