(mysql.info) adding-functions

 
 24.2 Adding New Functions to MySQL
 ==================================

 
* udf-features                 Features of the User-Defined Function Interface
* create-function              `CREATE FUNCTION' Syntax
* drop-function                `DROP FUNCTION' Syntax
* adding-udf                   Adding a New User-Defined Function
* adding-native-function       Adding a New Native Function
 
 There are two ways to add new functions to MySQL:
 
    * You can add functions through the user-defined function (UDF)
      interface. User-defined functions are compiled as object files and
      then added to and removed from the server dynamically using the
      `CREATE FUNCTION' and `DROP FUNCTION' statements. See 
      create-function.
 
    * You can add functions as native (built-in) MySQL functions.
      Native functions are compiled into the `mysqld' server and become
      available on a permanent basis.
 
 Each method has advantages and disadvantages:
 
    * If you write user-defined functions, you must install object files
      in addition to the server itself. If you compile your function
      into the server, you don't need to do that.
 
    * Native functions require you to modify a source distribution.
      UDFs do not. You can add UDFs to a binary MySQL distribution.  No
      access to MySQL source is necessary.
 
    * If you upgrade your MySQL distribution, you can continue to use
      your previously installed UDFs, unless you upgrade to a newer
      version for which the UDF interface changes. For native functions,
      you must repeat your modifications each time you upgrade.
 
 Whichever method you use to add new functions, they can be invoked in
 SQL statements just like native functions such as `ABS()' or
 `SOUNDEX()'.
 
 Another way to add functions is by creating stored functions.  These
 are written using SQL statements rather than by compiling object code.
 The syntax for writing stored functions is described in 
 stored-procedures.
 
 The following sections describe features of the UDF interface, provide
 instructions for writing UDFs, discuss security precautions that MySQL
 takes to prevent UDF misuse, and describe how to add native mySQL
 functions.
 
 For example source code that illustrates how to write UDFs, take a look
 at the `sql/udf_example.cc' file that is provided in MySQL source
 distributions.

Info Catalog

(mysql.info) mysql-internals

(mysql.info) extending-mysql

(mysql.info) adding-procedures

automatically generated byinfo2html

(mysql.info) adding-functions

Menu