SQL Standards
The first official standard for SQL was adopted by American
National Standards Institute(ANSI) in 1986. This standard was slightly
revised in 1989 and came to be known as "SQL-89" or "SQL1" standard.
The next official standard was released in October 1992 with some major
changes to the previously existing standard. The latest standard is
referred to as SQL-2003 and contains several important enhancements to
the previous versions.
Emergence Of Different Dialects
Even though SQL was accepted as a standard query language in
the relational database environment as early as the late 70s, it could
not stop the emergence of different SQL dialects because of various
reasons. Some of those reasons are outlined below
-
The original SQL standard in 1986 was not comprehensive
enough and database vendors had to innovate in order to meet the
growing customer demand for new features
-
The standardization of syntax for new features was not
proactive. Most of the advanced features were done after the vendors
came up with their own syntax for the advanced features
-
There was not much of an incentive for database vendors
to go back and support a standard syntax as their customers were
already getting used to the proprietary syntax
-
The competitive pressures among various database vendors
make them introduce new capabilities into their existing RDBMS
technology. These capabilities further compounds the differences among
the various existing databases
-
Last but not the least, all vendors pay only lip service
to standards and most of the time want to lock their customers into
their product through proprietary extensions to standard
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