PL/SQL - Procedural Language/Structured Query Language (PL/SQL) is
Oracle Corporation's propretary extension to the
SQL language.
Since SQL is a declarative language some constructs, such as loops, are impossible in it. PL/SQL is a
Turing-complete procedural language which fills in these gaps and allows Oracle
database developers to interface with the underlying
relational database. PL/SQL functions can be called from SQL code.
PL/SQL is analogous to the embedded procedural languages for other relational databases. Sybase? and its derivative [Microsoft SQL Server]? have Transact-SQL, PostgreSQL has Pg/SQL, and Oracle also allows Java to be used.