SQL-92 was the third revision of the SQL database query language. Unlike SQL-89, it was a major revision of the standard. Aside from a few minor incompatibilities, the SQL-89 standard is forward-compatible with SQL-92.
Contents
The standard specification itself grew about five times compared to SQL-89. Much of it was due more precise specifications of existing features; the increase due to new features was only by a factor of 1.5–2. Many of the new features had already been implemented by vendors before the new standard was adopted. However, most of the new features were added to the "intermediate" and "full" tiers of the specification, meaning that conformance with SQL-92 entry level was scarcely any more demanding than conformance with SQL-89.
Later revisions of the standard include SQL:1999 (SQL3), SQL:2003, SQL:2008, and SQL:2011.
New features
Significant new features include:
DATE, TIME, TIMESTAMP, INTERVAL, BIT string, VARCHAR strings, and NATIONAL CHARACTER strings.UNION JOIN, NATURAL JOIN, set differences, and set intersections.CASE. For an example, see Case (SQL).ALTER and DROP.CHECK constraint.SELECT * FROM INFORMATION_SCHEMA.TABLES;.CREATE TEMP TABLE etc.CAST (expr AS type).Extensions
Two significant extensions were published after standard (but before the next major iteration.)