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SQL (Structured Query Language)
FamilyQuery language
Designed byDonald D. Chamberlin
Raymond F. Boyce
DeveloperISO/IEC JTC 1 (Joint Technical Committee 1) / SC 32 (Subcommittee 32) / WG 3 (Working Group 3)
First appeared1974 (1974)
Stable release
SQL:2016 / December 2016 (2016-12)
Typing disciplineStatic, strong
Major implementations
Influenced by
SQL (file format)
Filename extension
Internet media type
Developed byISO/IEC
Initial release1986 (1986)
Type of formatDatabase
StandardISO/IEC 9075
Open format?Yes

Structured Query Language, abbreviated as SQL,(/ˈskwəl/ "sequel", /ˌɛsˌkjuːˈɛl/ (listen) S-Q-L; )[4][5] is a domain-specific language used in programming and designed for managing data held in a relational database management system (RDBMS), or for stream processing in a relational data stream management system (RDSMS). It is particularly useful in handling structured data, i.e. data incorporating relations among entities and variables.

SQL offers two main advantages over older read–write APIs such as ISAM or VSAM. Firstly, it introduced the concept of accessing many records with one single command. Secondly, it eliminates the need to specify how to reach a record, e.g. with or without an index.

Originally based upon relational algebra and tuple relational calculus, SQL consists of many types of statements,[6] which may be informally classed as sublanguages, commonly: a data query language (DQL),[a] a data definition language (DDL),[b] a data control language (DCL), and a data manipulation language (DML).[c][7] The scope of SQL includes data query, data manipulation (insert, update, and delete), data definition (schema creation and modification), and data access control. Although SQL is essentially a declarative language (4GL), it also includes procedural elements.

SQL was one of the first commercial languages to use Edgar F. Codd’s relational model. The model was described in his influential 1970 paper, "A Relational Model of Data for Large Shared Data Banks".[8] Despite not entirely adhering to the relational model as described by Codd, it became the most widely used database language.[9][10]

SQL became a standard of the American National Standards Institute (ANSI) in 1986 and of the International Organization for Standardization (ISO) in 1987.[11] Since then, the standard has been revised to include a larger set of features. Despite the existence of standards, most SQL code requires at least some changes before being ported to different database systems.

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  5. ^ Chamberlin, Donald D. (2001-10-03). "Oral history interview with Donald D. Chamberlin". Retrieved 2020-01-14. We changed the original name "SEQUEL" to SQL because we got a letter from somebody’s lawyer that said the name "SEQUEL" belonged to them. We shortened it to SQL, for Structured Query Language, and the product was known as SQL/DS.
  6. ^ SQL-92, 4.22 SQL-statements, 4.22.1 Classes of SQL-statements "There are at least five ways of classifying SQL-statements:", 4.22.2, SQL statements classified by function "The following are the main classes of SQL-statements:"; SQL:2003 4.11 SQL-statements, and later revisions.
  7. ^ Chatham, Mark (2012). Structured Query Language By Example - Volume I: Data Query Language. p. 8. ISBN 978-1-29119951-2.
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  11. ^ Cite error: The named reference ISO 9075:1987 was invoked but never defined (see the help page).

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