The first release of SQL was in June 1974. Designed at IBM by Donald D. Chamberlin and Raymond F. Boyce, it was based on the relational model proposed by E.F. Codd. SQL became the most widely used database language with many dialects, the most recent being SQL 2023.

SQL stands for Structured Query Language and was originally pronounced, and still is by many. as "sequel", although "S-Q-L" is the more modern way to say it. It is described by Wikipedia as:

a domain-specific language used to manage data, especially in a relational database management system (RDBMS). It is particularly useful in handling structured data, i.e., data incorporating relations among entities and variables.

Its scope includes data query, data manipulation (insert, update, and delete), data definition (schema creation and modification), and data access control. 

Being heavily influenced by the model described by E F Codd in his seminal 1970 paper A relational model of data for large shared data banks, SQL introduced the concept of accessing many records with one single command.

SQL has a distinctive syntax involving several language elements, such as clauses, expressions, predicates, queries and statements and, because white-space is generally ignored in SQL statements and queries, SQL code can be formatted for readability:

Source: Wikipedia: A chart showing several of the SQL language elements comprising a single statement. 

The two people credited as the developers of SQL are Don Chamberlin and Ray Boyce. Having taken their PhDs at Stanford and Purdue in 1972 they were recent hires at the IBM T.J. Watson Research Center in New York where they devised a first attempt at a relational database language, SQUARE (Specifying Queries in A Relational Environment), but it was difficult to use due to subscript/superscript notation.

It was after meeting Ted Codd, who was a computer scientist at IBM's San Jose Research Laboratory, at a symposium in 1972, that Boyce and Chamberlin believed that it should be possible to design a relational language that would be accessible to users without formal training in math or computer programming.

In an article in 2012 for the Anecdotes section of the IEEE Annals of the History of Computing, Chamberlin wrote 

For Ray and me, our exposure to the relational data model at Codd's research symposium was a revelation. For the first time, we could see how a query that would require a complex program in the DBTG language could be reduced to a few simple lines using one of Codd's relational languages. It became a game for the two of us to invent queries and challenge each other to express them in various query languages.

In 1973 they both moved to San Jose where work was ongoing on IBM's quasi-relational database management system, System R, project and started work on a successor to SQUARE, called SEQUEL, which would evolve into the SQL standard.

According to Wikipedia, the name SEQUEL was a pun on QUEL, the query language devised at Ingres and that it was later changed to SQL (dropping the vowels) because "SEQUEL" was a trademark of the UK-based Hawker Siddeley Dynamics Engineering Limited company. Only later did SQL become the acronym for "Structured Query Language".  

In this video in DataCamp's Data Framed series, recorded to mark SQL's 50th Anniversary. Don Chamberlin talks to Richie Cotton, Data Evangelist about the creation and development of SQL.

Watch to discover how SQL became standardized, how it evolved and spread via open source and how Chamberlin envisages the future of SQL through NoSQL and SQL++ and much more.

More Information

Early History of SQL

Related Articles

Codd and his Twelve Database Rules

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