SQL

SQL (Structured Query Language)
ParadigmDeclarative
FamilyQuery language
Designed byDonald D. Chamberlin
Raymond F. Boyce
DeveloperISO/IEC
First appeared1974 (1974)
Stable release
SQL:2016 / December 2016 (2016-12)
Typing disciplineStatic, strong
OSCross-platform
Websitewww.iso.org/standard/63555.html
Major implementations
Many
Dialects
Influenced by
Datalog
Influenced
CQL, LINQ, SPARQL, SOQL, PowerShell,[1] JPQL, jOOQ, N1QL
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/63555.html

SQL (/ˌɛsˌkjuːˈɛl/ (About this soundlisten) S-Q-L,[4] /ˈskwəl/ "sequel"; Structured Query Language)[5][6][7] 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,[8] 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][9] 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 utilize 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".[10] Despite not entirely adhering to the relational model as described by Codd, it became the most widely used database language.[11][12]

SQL became a standard of the American National Standards Institute (ANSI) in 1986, and of the International Organization for Standardization (ISO) in 1987.[13] 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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  8. ^ 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.
  9. ^ Chatham, Mark (2012). Structured Query Language By Example - Volume I: Data Query Language. p. 8. ISBN 978-1-29119951-2.
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