SQL was initially developed by IBM in the early 1970s and was called SEQUEL (Structured English Query Language) which was designed to process the data stored in IBM's database management systems.

The name SEQUEL was later changed to SQL becasue of trade mark practices which then became the acronym for the Structured Query Language. source

SQL is a 4th generation programming language referred by 4gl that is used for storing, retriveing and manipluating data in data bases. For understanding the evolution of the programming languages, going back to first generation could be helpful as they were made of binary numbers that is 1s and 0s. Considering that, the 4th generation languages can be seen as very high level. This concept is very much relative.