SQL
SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce after learning about the relational model from Ted Codd in the early 1970s. This version, initially called "SEQUEL" ("Structured English Query Language"), was designed to manipulate and retrieve data stored in IBM's original quasi-relational database management system, System R, which a group at IBM San Jose Research Laboratory had developed during the 1970s.
SQL/XML
SQL/XML or XML-Related Specifications is part 14 of the Structured Query Language (SQL) specification. In addition to the traditional predefined SQL data types like codice_1 it introduces the predefined data type codice_2 together with constructors, several routines, functions, and XML-to-SQL data type mappings to support manipulation and storage of XML in a SQL database.The specification defines the data type codice_2, functions for working with XML, including element construction, mapping data from relational tables, combining XML fragments, and embedding XQuery expressions in SQL statements. Functions which can be embedded include XMLQUERY (which extracts XML or values from an XML field) and XMLEXISTS (which predicates whether an XQuery expression is matched).