The name SEQUEL was later changed to SQL (dropping the vowels) because "SEQUEL" was a trademark of the UK-based Hawker Siddeley Dynamics Engineering Limited company. After moving to the San Jose Research Laboratory in 1973, they began work on a sequel to SQUARE. Ĭhamberlin and Boyce's first attempt at a relational database language was SQUARE (Specifying Queries in A Relational Environment), but it was difficult to use due to subscript/superscript notation. This version, initially called SEQUEL (Structured English Query Language), was designed to manipulate and retrieve data stored in IBM's original quasirelational database management system, System R, which a group at IBM San Jose Research Laboratory had developed during the 1970s. Boyce after learning about the relational model from Edgar F. SQL was initially developed at IBM by Donald D. 12.1.1 ITTF publicly available standards and technical reports.4.4.2 Extensions to the ISO/IEC Standard.Despite the existence of standards, most SQL code requires at least some changes before being ported to different database systems. Since then, the standard has been revised to include a larger set of features. SQL became a standard of the American National Standards Institute (ANSI) in 1986, and of the International Organization for Standardization (ISO) in 1987. Despite not entirely adhering to the relational model as described by Codd, it became the most widely used database language. The model was described in his influential 1970 paper, "A Relational Model of Data for Large Shared Data Banks". SQL was one of the first commercial languages to use Edgar F.
Although SQL is essentially a declarative language ( 4GL), it also includes procedural elements. The scope of SQL includes data query, data manipulation (insert, update and delete), data definition ( schema creation and modification), and data access control. Originally based upon relational algebra and tuple relational calculus, SQL consists of many types of statements, which may be informally classed as sublanguages, commonly: a data query language (DQL), a data definition language (DDL), a data control language (DCL), and a data manipulation language (DML).
Secondly, it eliminates the need to specify how to reach a record, e.g. Firstly, it introduced the concept of accessing many records with one single command. SQL offers two main advantages over older read–write APIs such as ISAM or VSAM. data incorporating relations among entities and variables. It is particularly useful in handling structured data, i.e. SQL ( / ˌ ɛ s ˌ k juː ˈ ɛ l/ ( listen) S-Q-L, / ˈ s iː k w əl/ "sequel" Structured Query Language) 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).
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