SQL2003

SQL2003, formally ISO/IEC 9075:2003, is a revision of the SQL standard published in 2003 as part of the ISO/IEC SQL family. It followed earlier SQL revisions and provided a set of language features intended to improve portability and expressiveness for relational database systems. The edition is implemented as a modular standard, covering core SQL syntax as well as extensions and optional components.

Key features introduced or clarified in SQL2003 include enhanced support for XML. It standardizes the handling of XML data through the SQL/XML specifications, enabling storage and querying of XML within SQL databases. This includes data types and functions designed to bridge relational data with XML documents, facilitating interoperability between SQL and XML-based applications.

Another notable addition is the MERGE statement, which allows conditional INSERT, UPDATE, or DELETE operations in a single statement. This capability supports more efficient upsert workflows and complex data synchronization scenarios.

SQL2003 also expanded analytical and object-relational capabilities. It introduced analytic (window) functions to perform calculations across sets of rows related to the current query, enabling operations such as ranking and moving aggregates. In addition, the standard broadened support for object-relational features, including structured and reference types, and the ability to attach methods to user-defined types, enhancing the modeling of complex data.

As with other SQL standards, actual support for SQL2003 features varies by database system. Many vendors implemented a subset or extended versions of these features, with enterprise databases adopting XML, MERGE, and analytic functions over subsequent years.