Like any technology that strives to be interoperable among different implementations, SQL has been standardized. The first SQL standard was adopted and published by the American National Standards Institute (ANSI) in 1986. The standard was further ratified by the International Organization for Standardization (ISO) in 1987, and ISO continues to be the primary international standardization body for SQL.

SQL Standardization

The most recent standardization of SQL is SQL:2006, though SQL:2006 is ultimately concerned with the relationship between SQL and XML and not the further development of SQL itself.

When considering SQL syntax and functionality today, the SQL-92 and SQL:1999 standards are typically used, as they were the last major updates to SQL that were concerned with bettering the language, rather than extending it into arguably unnecessary territory.

SQL:2003 also contains some less well-known but still important parts of SQL, including window functions and standardized sequences, along with some initial XML-related features. Notably, SQL:2003 also removed the BIT and BIT VARYING data types, which were overwhelmingly poorly implemented and underused.

The ANSI SQL standard was published in 1986 as SQL-86 but was not ratified by ISO until 1987; as such, it is sometimes called SQL-87. Minor revisions were made to that original standard in 1989, under the document name SQL-89.

A relatively complete revision of every part of the SQL standard is expected some time in 2007.

Prominent revisions of the SQL standard are summarized in Table 1.

Table 1. Revisions of SQL standards

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