Editing Sublanguage (section)

==In relational database theory==

In [[relational database]] theory, the term "sublanguage", first used for this purpose by [[Edgar F. Codd|E. F. Codd]] in 1970, refers to a [[computer language]] used to define or manipulate the structure and contents of a [[relational database management system]] (RDBMS). Typical sublanguages associated with modern RDBMS's are [[Query by Example|QBE]] (Query by Example) and [[SQL]] (Structured Query Language). In 1985, Codd encapsulated his thinking in twelve rules which every database must satisfy in order to be truly relational.<ref>{{cite news |last1=Codd |first1=E |title=Computer World |work=Is Your DBMS Really Relational? |date=October 14, 1985}}</ref><ref>{{cite news |last1=Codd |first1=E |title=Computer World |work=Does Your DBMS Run By The Rules? |date=October 21, 1985}}</ref> The fifth rule is known as the ''Comprehensive data sublanguage rule'', and states:

: ''A relational system may support several languages and various modes of terminal use (for example, the fill-in-the-blanks mode). However, there must be at least one language whose statements are expressible, per some well-defined syntax, as character strings, and that is comprehensive in supporting all of the following items:''
:* ''Data definition''
:* ''View definition''
:* ''Data manipulation (interactive and by program)''
:* ''Integrity constraints''
:* ''Authorization''
:* ''Transaction boundaries (begin, commit, and rollback)''