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SQL

This article is about the database language. For other uses, see SQL (disambiguation).
"SEQUEL" redirects here. For the topic of the word, see sequel. For other uses, see Sequel (disambiguation).
SQL (Structured Query Language)
ParadigmDeclarative
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:2023 / June 2023 (2023-06)
Typing disciplineStatic, strong
OSCross-platform
Websitewww.iso.org/standard/76583.html
Major implementations
Many
Dialects
Influenced by
Datalog
Influenced
CQL, LINQ, SPARQL, SOQL, PowerShell,[1] JPQL, jOOQ, N1QL, GQL
SQL (file format)
Filename extension
.sql
Internet media type
application/sql[2][3]
Developed byISO/IEC
Initial release1986 (1986)
Type of formatDatabase
StandardISO/IEC 9075
Open format?Yes
Websitewww.iso.org/standard/76583.html

Structured Query Language (SQL) (pronounced /ˌɛsˌkjuˈɛl/ S-Q-L; or alternatively as /ˈsiːkwəl/ "sequel")[4][5] is 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.

Introduced in the 1970s, SQL offered 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, i.e., 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: Data query Language (DQL), Data Definition Language (DDL), Data Control Language (DCL), and Data Manipulation Language (DML).[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, SQL 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 multiple times to include a larger set of features and incorporate common extensions. Despite the existence of standards, virtually no implementations in existence adhere to it fully, and most SQL code requires at least some changes before being ported to different database systems.

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  3. ^ Cite error: The named reference application/sql was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference learningSQL was invoked but never defined (see the help page).
  5. ^ Chamberlin, Donald D.; Frana, Philip L. (3 October 2001). "Oral history interview with Donald D. Chamberlin". University Digital Conservancy. hdl:11299/107215. Retrieved 14 January 2020. 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. Lulu.com. p. 8. ISBN 9781291199512.
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  10. ^ Cite error: The named reference IBM-sql was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference ISO 9075:1987 was invoked but never defined (see the help page).

SQL

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