SQL

SQL (/ˌɛs.kjuːˈɛl/ ( listen) ESS-kew-EL^[4] or /ˈsiːkwəl/ ( listen) SEE-kwəl or /ˈskwil/ ( listen) SKWEEL,^[5] Structured Query Language^[6][7][8][9]) is a domain-specific language used in programming and designed for managing data held in arelational database management system (RDBMS), or for stream processing in a relational data stream management system (RDSMS). In comparison to older read/write APIs like ISAM or VSAM, SQL offers two main advantages: first, it introduced the concept of accessing many records with one single command; and second, 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 a data definition language, data manipulation language, and data control language. The scope of SQL includes data insert, query, update and delete,schema creation and modification, and data access control. Although SQL is often described as, and to a great extent is, a declarative language (4GL), it also includes procedural elements.