This chapter discusses the history and fundamental concepts of SQL and forms the foundation for the next chapter, which
is about applying SQL with PostgreSQL. It addresses the basics of relational databases, object-related database extensions, the
structure of a SQL statement, and provides an overview of PostgreSQL-supported data types, operators and functions.
SQL, the
Structured Query Language
, is a mature, powerful, and versatile relational
query language. The history of SQL extends back to IBM research begun in 1970. The next few sections discuss
the history of SQL, its predecessors, and the various SQL standards that have developed over the years.
