This guide documents the changes made in the Firebird SQL language between InterBase 6 and Firebird 2.5.1.

It covers the following areas:

• Reserved words
• Data types and subtypes
• DDL statements (Data Definition Language)
• DML statements (Data Manipulation Language)
• Transaction control statements
• PSQL statements (Procedural SQL, used in stored procedures and triggers)
• Security and access control statements
• Context variables
• Operators and predicates
• Aggregate functions
• Internal functions
• UDFs (User Defined Functions, also known as external functions)

To have a complete Firebird 2.5 SQL reference, you need:

• The InterBase 6.0 beta SQL Reference (LangRef.pdf and/or SQLRef.html)
• This document

Non-SQL topics are not discussed in this document. These include:

• ODS versions
• Bug listings
• Installation and configuration
• Upgrade, migration and compatibility
• Server architectures
• API functions
• Connection protocols
• Tools and utilities

Consult the Release Notes for information on these subjects. You can find the Release Notes and other documentation via the Firebird Documentation Index at https://www.firebirdsql.org/en/documentation/.

This document covers all Firebird versions up to and including 2.5.

Most of this document was written by the main author. The remainder (2–3%) was lifted from various Firebird Release Notes editions, which in turn contain material from preceding sources like the Whatsnew documents.

Authors and editors of the included material are:

• J. Beesley
• Helen Borrie
• Arno Brinkman
• Frank Ingermann
• Vlad Khorsun
• Alex Peshkov
• Nickolay Samofatov
• Adriano dos Santos Fernandes
• Dmitry Yemanov

Vlad Khorsun, Adriano dos Santos Fernandes and Dmitry Yemanov have been very helpful and patient whenever I had questions about the details of various new Firebird features. The email conversations I had with them have made this a better work of reference. Thank you, guys!