Extensible function set.

    Interbase tries to be standard and it took the minimal approach with built-in functions that can be used in SQL statements: it provides a few: AVG, CAST, COUNT, MAX, MIN, SUM and UPPER. There's no predefined string manipulation routines or date manipulation routines (some enhancements were expected in version 6).

Saying the original function that shipped with the server are a small bunch is not the same as saying the server cannot be extended. In fact, thinking is this possibility, IB developers opened the door to make the server extensible. The trick is allowing users to write their own extensions to the server and integrate them by declaring the functions in each database where they are needed. At this time, there's no server hook so they can be defined once for all possible databases. The extensions are named UDFs, short for User Defined Functions.

Probably you don't need to worry about learning UDF conventions in the most common cases: Interbase has covered you with the most common functions in the form of a library that exists on both Windows and Solaris at this time. This library is free for you and was written by Greg A. Deatz, a longtime IB developer. It's called FreeUDFLib and in Windows is a dynamic link library (DLL) written in Delphi. In Linux and UNIX, it's written in C and is called FreeUDFLibC. This plug-and-play solution includes the script to make any IB database aware of the new functions. Also, because you can read the source code, you can understand how an UDF is written in order to work smoothly in the server.

This page was last updated on 2000-05-26 04:28:46