0 Introduction to SQL

SQL stands for Structured Query Language. It enables you to create and operate relational database which are sets of related information stored in tables.
The database world has becoming increasingly integrated , and this has led to a clamor for a standard language that can be used to operate in many different kinds of computer environment.The SQL has proved to be a standard language as it allows users to learn one set of commands and use it to create, retrieve,alter and transfer information regardless of whether they are working on a PC, a workstation, a mini, or a mainframe.
There are numerous versions of SQL. The original version was developed by IBM's San Lose Research Laboratory(now the American Research center). This language , originally called Sequel, was implemented as part of the System R project in early 1970s. The Sequel language has evolved since then and its name has changed to SQL. In 1986, the American National Standards Institute(ANSI) published an SQL standard that was updated again in 1192.
  SQL has clearly established itself as the standard relational database language.