Languages

Database languages are special-purpose
languages, which do one or more of the
following:
Data definition language – defines data types
and the relationships among them
Data manipulation language – performs tasks
such as inserting, updating, or deleting data
occurrences
Query language – allows searching for
information and computing derived information
Database languages are specific to a particular
data model. Notable examples include:
SQL combines the roles of data definition,
data manipulation, and query in a single
language. It was one of the first commercial
languages for the relational model, although it
departs in some respects from the relational
model as described by Codd (for example, the
rows and columns of a table can be ordered).
SQL became a standard of the American
National Standards Institute (ANSI) in 1986, and
of the International Organization for
Standardization (ISO) in 1987. The standards
have been regularly enhanced since and is
supported (with varying degrees of
conformance) by all mainstream commercial
relational DBMSs. [27][28]
OQL is an object model language standard
(from the Object Data Management Group ). It
has influenced the design of some of the newer
query languages like JDOQL and EJB QL .
XQuery is a standard XML query language
implemented by XML database systems such as
MarkLogic and eXist, by relational databases
with XML capability such as Oracle and DB2,
and also by in-memory XML processors such
as Saxon .
SQL/XML combines XQuery with SQL. [29]
A database language may also incorporate
features like:
DBMS-specific Configuration and storage
engine management
Computations to modify query results, like
counting, summing, averaging, sorting,
grouping, and cross-referencing
Constraint enforcement (e.g. in an
automotive database, only allowing one engine
type per car)
Application programming interface version of
the query language, for programmer
convenience