Small correction. For the product SQL Server, the correct pronouciation is "sequel server". In the (then still printed) product documentation of SQL Server 4.21, the "correct" explanation was explicitly included on one of the first pages.

However, the language "SQL" (which is used, in different dialects, by different RDBMSes) should be pronounced "es-queue-el", since this is an abbreviationm. (For "Structured Query Language" - but I'm sure you already knew that).

Interestingly, the dialect of SQL (es queue el) that is implemented by SQL (sequel) Server is called T-SQL - which is pronounced "tee sequel" (aka cup-o-tea part 2), even though this is an abbreviation for Transact-SQL (Transact es queue el).