Datasheet

SQL and Relational Database Management Systems 1
SQL:1999 (SQL3)
SQL:1999 represented the next step in SQL standards development. The efforts to define this standard
began over a year before its predecessor — SQL-92 (SQL2) — was adopted. The new standard was
developed under the guidance of both the ANSI and ISO committees, and the change introduced
into the database world by SQL3 a dramatic shift from a nonrelational to a relational database model.
Its sheer complexity is reflected in the number of pages describing the standard — 2,000 pages
compared to 120 or so pages for SQL-89 and 628 pages for SQL-92. Some of the defined standards
(for example, stored procedures) existed as vendor-specific extensions; some of them (like OOP) are
completely new to SQL proper. SQL3 was released as an ANSI/ISO draft standard in 1999; later the
same year, its status was changed to a standard level.
SQL3 extends traditional relational data models to incorporate objects and complex data types
within the relational tables, along with all supporting mechanisms. It brings into SQL all the
major OOP principles, namely inheritance, encapsulation,andpolymorphism (all of which are
beyond the scope of this book) in addition to ‘‘standard’’ SQL features defined in SQL-92. It
provides seamless integration with the data consumer applications designed and implemented in
OO languages (SmallTalk, Eiffel, and so on).
SQL standards are becoming more and more dynamic. For example, between 1992
and 1999, the years of major SQL standards releases, two parts were added to SQL
standards, SQL/CLI and SQL/PSM, in 1995 and 1996, correspondingly.
SQL:2003
The big topic in SQL:2003 is XML. In addition, there are some minor modifications and ‘‘bug
fixes’’ to the SQL:1999 standard, as well as a couple of new features, such as table functions,
sequence generators, auto-generated values, identity-columns, and some modifications to DML
(
MERGE)and DDL (CREATE TABLE LIKE and CREATE TABLE AS) syntax. Also, a couple of
obsolete data types have been removed (
BIT and BIT VARYING) and a few new data types have
been added (
BIGINT, MULTISET,andXML).
SQL:2003 consists of nine parts: SQL/Framework (information common to all parts of the stan-
dard), SQL/Foundation (data definition and data manipulation syntax and semantics), SQL/CLI
(Call Level Interface / ODBC), SQL/PSM (Persistent Stored Modules — procedural language
extensions), SQL/MED (Management of External Data — external OS files access), SQL/OLB
(Object Language Bindings — syntax of embedding SQL in Java), SQL/Schemata (Metadata),
SQL/JRT (Java Routines and Types), and SQL/XML (XML-related specifications in SQL). It’s
3,606 pages, which is almost twice as long as the previous SQL standard.
SQL:2008
Yet another revision of SQL standards is expected to be released in 2008. The XML section,
which was already significantly changed and enlarged in 2006, is being revised again. Also, some
other minor changes to various sections are pending. The new SQL:2008 features will likely in-
clude a new
BINARY data type, regular expression support, and, possibly, materialized views and
FIRST n / TOP n queries.
25