SQL (/ˌɛsˌkjuːˈɛl/ (About this soundlisten) S-Q-L, /ˈsiːkwəl/ "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). 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, 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] 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". Despite not entirely adhering to the relational model as described by Codd, it became the most widely used database language.
SQL became a standard of the American National Standards Institute (ANSI) in 1986, and of the International Organization for Standardization (ISO) in 1987. 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.
Burton upon Trent, also known as Burton-on-Trent or simply Burton, is a market town in Staffordshire, England, close to the border with Derbyshire. In 2011, it had a population of 72,299. The demonym for residents of the town is 'Burtonian'. Burton is 11 miles (18 km) southwest of Derby, 27 miles (43 km) northwest of Leicester, 28 miles (45 km) west-southwest of Nottingham and 20 miles (32 km) south of the southern entrance to the Peak District National Park.
Burton is known for brewing. The town originally grew up around Burton Abbey. Burton Bridge was also the site of two battles, in 1322 when Edward II defeated the rebel Earl of Lancaster and 1643 when royalists captured the town during the First English Civil War. William Lord Paget and his descendants were responsible for extending the manor house within the abbey grounds and facilitating the extension of the River Trent Navigation to Burton. Burton grew into a busy market town by the early modern period.
The town is served by Burton-on-Trent railway station. The town was also the start and terminus of the now defunct South Staffordshire Line which linked it to Lichfield, Walsall, Dudley and Stourbridge.