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Lesson2 What is SQL?
Objective Understand what SQL is and how it was conceived.

How was SQL Defined and Conceived?

Structured Query Language (SQL) is an English-based element that provides you with the ability to ask questions of a database and get answers to those questions.
SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce in the early 1970s. This version, initially called SEQUEL (Structured English Query Language), was designed to manipulate and retrieve data stored in IBM's original quasi-relational database management system, System R, which a group at IBM San Jose Research Laboratory had developed during the 1970s. The acronym SEQUEL was later changed to SQL because "SEQUEL" was a trademark of the UK-based Hawker Aircraft Company. In the late 1970s, Relational Software, Inc. (now Oracle Corporation) saw the potential of the concepts described by Codd, Chamberlin, and Boyce and developed their own SQL-based RDBMS with aspirations of selling it to the U.S. Navy, Central Intelligence Agency, and other U.S. government agencies. In June 1979, Relational Software, Inc. introduced the first commercially available implementation of SQL, Oracle V2 (Version2) for VAX computers. After testing SQL at customer test sites to determine the usefulness and practicality of the system, IBM began developing commercial products based on their System R prototype including System/38, SQL/DS, and DB2, which were commercially available in 1979, 1981, and 1983, respectively.

The user interacts with the database by means of the computer
Client machine communicates with 1) database on local machine or 2) remote database on a database server

SQL is a bit different from developing applications that gather this information from the database by manipulating the database directly.
In those cases, the application is responsible for determining how the information is analyzed and retrieved.
With SQL, you do not have to indicate how you want information retrieved, you only indicate what criteria you want to use.
This is called a declarative language.


A declarative language is a language in which you simply indicate what you need and let the database engine get it for you. How the information is actually gathered is irrelevant to the user.
In the next lesson, a sample SQL statement will be examined.