Brief Background
Although the first official SQL specification was published in 1986 by the American National Standards Institute (ANSI), the language traces its roots back to the early 1970s and the pioneering relational database work that was being done at IBM. Current SQL standards are ratified and published by the International Standards Organization (ISO). Although a new standard is published every few years, the last significant set of changes to the core language can be traced to the SQL:1999 standard (also known as “SQL3”). Subsequent standards have mainly been concerned with storing and processing XML-based data. Overall, the evolution of SQL is firmly rooted in the practical aspects of database development, and in many cases new standards only serve to ratify and standardize syntax or features that have been present in commercial database products for some time.
Declarative
The core of SQL is a declarative language. In a declarative language, you state what you want the results to be and allow the language processor to figure out how to deliver the desired results. Compare this to imperative languages, such as C, Java, Perl, or Python, where each step of a calculation or operation must be explicitly written out, leaving it up to the programmer to lead the program, step by step, to the correct conclusion.
The first SQL standards were specifically designed to make the language approachable and usable by “non-computer people”—at least by the 1980s definition of that term. This ...